Deciphering the biology of KIR2DL3+ T lymphocytes that are associated to relapse in haploidentical HSCT

KIR are mainly expressed on NK cells and to a lesser extent on T lymphocytes. Although the KIR NK cell repertoire was well explored in haploidentical Hematopoietic Stem Cell Transplantation (HSCT), KIR T cell compartment remains to be investigated in this context. In this study, the investigation of NK receptors on T lymphocytes during immune reconstitution after T-cell-replete haploidentical HSCT with Post-Transplant Cyclophosphamide (PTCy) has shown a significant increase of KIR2DL2/3+ T cell frequency at day 25. This was especially observed at day 30 in recipients who relapsed. IL-15 but not IL-12 increased in vitro KIR+ T cell expansion suggesting that the raised IL-15 serum concentration observed after PTCy in haploidentical HSCT might increase KIR+ T cell frequency. Moreover, investigations from healthy blood donors showed a higher inhibiting effect of KIR2DL3 on CMV specific T cell response against allogeneic than autologous C1+ target cells. The association of KIR+ T cell subset with relapse may suggest that inhibitory KIR2DL2/3 limit anti-leukemic effect of specific T lymphocytes at this early step of immune reconstitution. Further phenotypic and mechanistic investigations on this cell subset from a broader cohort of HSCT recipients should clarify its potential implication in relapse occurrence. Our results demonstrate that KIR-HLA interactions known to modulate NK cell functions also modulate T cell immune responses in the context of allogeneic HSCT.

Distribution of the killer cell immunoglobulin-like receptors in Mexican Mestizos

Understanding the complex interaction between human leukocyte antigen (HLA) and killer immunoglobulin-like receptor (KIR) requires study of both HLA and KIR diversity in the same population. The presence of KIR genes 2DL1, 2, 3, 4, 5, KIR3DL1, 3DL2, 3DL3, KIR2DS1, 2DS2, 2DS3, 2DS4, 2DS5, KIR3DS1, KIR3DP1, KIR2DP1 was determined in 54 unrelated Mexican Mestizo donors. The PCR sequence-specific oligonucleotide probe One Lambda kit (Luminex) kindly given by J. Lee was used for typing. The software analyses the combination obtained for each of the five exons. Five controls (UCLA DNA exchange) were run as quality control. The gene frequency (GF) was calculated for the 16 KIR loci; the GF of individual genes was 100% for 2DL4, 3DL1, 3DL2, 3DL3, 3DP1. KIR2DL1 (76.43%), KIR2DL2 (37.64%), KIR2DL3 (76.43%), KIR2DL5 (29.29%), KIR3DS1 (23.02%), KIR2DS1 (21.83%), KIR2DS2 (37.64%), KIR2DS3 (50.93%), KIR2DS4 (86.93%), KIR2DS5 (29.29%), KIR2DP1 (86.39%). We observed similar frequencies with Caucasians and Mediterraneans, with exceptions: KIR3DL1 which was present in 100% Mexicans, ranged from 62% to 75% in Caucasians; 2DS3 (50.9%) vs 14-20% 2DS4 (86.39%) vs 65-79% and 2DS5 (29.29%) vs 11-18% in Caucasians. The finding of 23 phenotypes in 54 individuals accounting for both chromosomes, demonstrates the enormous diversity. We found 14 different combinations of stimulatory KIRs in the phenotypes; every subject had at least one stimulatory KIR; in all of them, 2DS4 existed except for one person who may have some new combination: 2DS2 2DS3. Extended family data will offer accurate and precise haplotypes to provide an insight on the significance of ethnic distribution and KIR repertoire.

KIR genes polymorphism in Argentinean Caucasoid and Amerindian populations

In natural killer cells, killer immunoglobulin-like receptors (KIRs) loci code for either inhibitory or activating receptors, and according to the number of genes present in each individual, it is possible to identify a high rate of polymorphism in the populations. We performed KIR typing by polymerase chain reaction-sequence-specific oligonucleotide probing in 402 Argentinean Caucasoid and in two Amerindian populations (101 Wichis and 54 Chiriguanos) from the North of Argentina. KIR2DL4, KIR3DL2, KIR3DL3 and KIR3DP1 were always present, whereas the frequencies of KIR2DL1, KIR2DL3, KIR2DS4, KIR3DL1 and KIR2DP1 ranged between 84% and 96%. The frequencies of KIR2DS2, KIR2DL2, KIR2DL5, KIR2DS5, KIR2DS1 and KIR3DS1 ranged between 41% and 62%. The KIR2DS3 with a frequency of 29% in Argentinean Caucasoid population was present at a very low frequency in Amerindian populations. Haplotype segregation studies performed in 10 Wichi families showed the presence of only three haplotypes: A, B5 and B1. The Amerindian populations showed several similarities to Asian but not to Caucasoid populations with regard to the frequency of KIR2DS3, full-length KIR2DS4 gene and KIR2DL4 alleles.

Reconstitution of Natural Killer Cell Receptor Repertoires after Unmanipulated HLA-Mismatched/Haploidentical Blood and Marrow Transplantation: Analyses of CD94:NKG2A and Killer Immunoglobulin-Like Receptor Expression and Their Associations with Clinical Outcome

The effect of natural killer (NK) cell alloreactivity on the outcome of haploidentical hematopoietic stem cell transplantation (HSCT), with or without in vitro T cell depletion, remains controversial. Killer immunoglobulin-like receptors (KIRs) recognize human leukocyte antigen C and B epitopes on target cells, thereby regulating NK cell activity. To examine the recovery of CD94:NKG2A and KIR (CD158a, CD158b, and CD158e) expression by NK cells, we used flow cytometry to evaluate samples from 24 patients and their donors before and in the year following unmanipulated HLA-haploidentical/mismatched blood and marrow transplantation. Linear regression analysis demonstrated that NKG2A recovery was inversely correlated with CD158b recovery in the year following transplant. The doses of T cell subgroups CD4+ and CD8+ were inversely associated with CD158a and CD158e expression during the 2 months following transplantation. Moreover, patients with grades II-IV acute graft-versus-host disease (aGVHD) or who received "high" doses of T cells (>1.37 x 10(8)/kg) showed delayed recovery of KIRs during the 2 months following transplantation. Univariate analysis showed that patients with high CD94 expression by day 60 (>90%) or who received donors with high CD94 expression (>80%) were associated with higher transplantation-related mortality (P = .006 or .067, respectively) and poorer leukemia-free survival (P = .012 or .094, respectively). Thus, the occurrence of aGVHD or the receipt of high doses of T cells in the allograft altered KIR reconstitution. Furthermore, high levels of CD94 expression in donors or in recipients by day 60 might be a good predictor for poor prognosis.

KIR receptors and HLA-C in the maintenance of pregnancy

The present study demonstrated that patients who have recurrent spontaneous abortions (RSA) presented a decreased number of killer immunoglobulin-like inhibitory receptors (KIR), in particular KIR2DL2. The KIR AA genotype was found increased in comparison with controls. Individuals AA will also be homozygous for 2DL3, which in contrast to 2DL2, show a weaker interaction with C1 ligands and therefore a weaker inhibition. The present study might support that in RSA patients, the balance between inhibitory and activating receptors present in natural killer cells is inclined toward an activating state that may contribute to pregnancy loss.

Low expression of CD161 and NKG2D activating NK receptor is associated with impaired NK cell cytotoxicity in metastatic melanoma patients

Natural killer (NK) cells play a role in the innate and adaptive antitumor immune responses. The activity of NK cells is regulated by functionally opposing, activating and inhibitory receptors whose balance ultimately determines whether target cells will be susceptible to NK cell mediated lysis. As melanoma is an immunogenic tumor, the effect of immunomodulating agents is consistently investigated. In this study in 79 metastatic melanoma (MM) patients and 52 controls NK activity, expression of activating NKG2D and CD161 receptors and KIR receptors, CD158a and CD158b, on freshly isolated PBL and NK cells were evaluated. Native NK cell activity of melanoma patients in clinical stage I-III and MM patients was determined against NK sensitive K562, NK resistant Daudi, human melanoma FemX, HeLa and HL 60 target tumor cell lines. In addition, predictive pretherapy immunomodulating effect after 18 h in vitro treatments of PBL of MM patients with rh IL-2, IFN-alpha (IFN), 13-cis retinoic acid (RA) and combination IFN-alpha and RA was evaluated with respect to NK cell lyses against K562 and FemX cell lines. In this study we show for the first time that low expression of CD161 and activating NKG2D receptors, without increased expression of KIR receptors CD158a and CD158b, as well as a decrease in the cytotoxic, CD16(bright) NK cell subset, is associated with a significant impairment in NK cell activity in MM patients. Furthermore, the predictive pretherapy finding that IL-2, IFN, IFN and RA, unlike RA alone, can enhance NK cell activity of MM patients against FemX melanoma tumor cell line can be of help in the design and development of therapeutic regimens, considering that it has recently been shown that low-dose combination of different immunomodulators represents the most promising approach in the therapy of MM.

Impaired natural killer cell lysis in breast cancer patients with high levels of psychological stress is associated with altered expression of killer immunoglobin-like receptors

BACKGROUND

We previously reported that cancer-related psychological stress is associated with reduced natural killer (NK) cell lysis. We hypothesized that reduced NK cell cytotoxicity in patients with increased levels of stress would correlate with alterations in the expression of inhibitory NK cell receptors (killer immunoglobulin-like receptors, or KIRs). The specific aim of this study was to examine KIR expression in patients with high or low levels of psychologic stress and correlate alterations in KIR expression with NK cell function.

MATERIALS AND METHODS

Two hundred twenty-seven patients underwent baseline evaluation of cancer-related psychological stress and were randomized to psychosocial intervention versus observation. From this population, two groups were defined based on pretreatment measurements of NK lytic activity, stress levels, and the availability of cryopreserved peripheral blood mononuclear cells (PBMC). Group I (n=9) had low stress by the Impact of Events Scale (IES), and high NK cell lysis at the 50:1 effector: target ratio (NK(50)=52-89%). Group II (n=8) had high stress and low NK(50) (27-52%). Lymphokine activated killer (LAK) activity, antibody dependent cellular cytotoxicity (ADCC), and expression of cytokine receptors, adhesion molecules, and killer immunoglobulin-like receptors (KIRs) were assessed in PBMC.

RESULTS

Incubation of PBMC with NK-stimulatory cytokines (IL-2, IL-12, or IL-15) led to significant increases in cytotoxic activity regardless of IES/NK(50) scores. There were no significant group differences in NK cell surface expression of the IL-2 receptor components CD25 and CD122, antibody-dependent lysis of HER2/neu-positive SKBr3 cells treated with an anti-HER2/neu monoclonal antibody, expression of adhesion molecules (CD2, CD11a, CD18) and markers of activation (CD69), or expression of the KIRs CD158a, NKG2a, NKB1, and CD161. However, levels of CD158b were significantly higher in Group I after incubation in media alone or with IL-2, and CD94 expression was significantly lower in Group I after incubation with IL-2.

CONCLUSIONS

In this study of a small subset of breast cancer patients chosen from a previous clinical trial of psychosocial intervention for breast cancer, impaired NK lysis in breast cancer patients with high levels of psychological stress was associated with alterations in surface expression of killer immunoglobulin-like receptors. However, immune effectors retained the ability to lyse antibody-coated targets and to initiate lymphokine-activated killer activity, irrespective of stress levels or baseline NK(50).

A single polymorphism disrupts the killer Ig-like receptor 2DL2/2DL3 D1 domain

Genetic polymorphisms found in the killer Ig-like receptor (KIR), two domains, long cytoplasmic tail 2/3 (KIR2DL2/3) locus are responsible for the differential binding of KIR2DL2/3 allelic products with their HLA-C ligands and have been associated with the resolution of hepatitis C infection. In our study, a KIR CD3zeta fusion-binding assay did not detect any interaction between the KIR2DL2*004 extracellular domain and several putative KIR2DL2/3 ligands. To determine the amino acid polymorphism(s) responsible for the KIR2DL2*004 phenotype, we mutated the polymorphic residues of full-length KIR and expressed them in human Jurkat cells. Flow cytometry analysis failed to detect the surface expression of receptors containing a threonine at position 41 (T41), a polymorphism specific to KIR2DL2*004. Confocal microscopy showed that receptors containing T41 were retained inside the cell and had a perinuclear localization, possibly indicating that their extracellular domain was misfolded. Most KIR2DL2/3 alleles possess an arginine at position 41 (R41), and we predicted through molecular modeling and demonstrated by mutagenesis that R41 most likely interacts with the nearby residues Y77 and D47. Interaction between these residues would maintain C strand contact with the C' and F strands of the D1 domain beta-sheet. Furthermore, R41 and Y77 are conserved in the C and F strand amino acid alignments of Ig-like superfamily members, and may therefore be necessary for the structural integrity of other immune response proteins. Our data indicate that the extracellular T41 polymorphism encoded by the KIR2DL2*004 allele most likely results in misfolding of the D1 domain and complete intracellular retention of the receptor.

[Polymorphism of killer cell immunoglobulin-like receptor gene and its correlation with leukemia]

The study was purposed to investigate the polymorphism of killer cell immunoglobulin-like receptor (KIR) gene of the patients with leukemia and to explore the correlation between the KIR gene and susceptibility of leukemia. The KIR genotype of 50 patients with leukemia and 60 healthy controls in northern. Hans were analyzed by PCR-SSP. The results indicated that the present known 18 KIR genes were detected and identified. The frequencies of KIR 3DL3, 3DL2 and 2DL4 were 100% in all subjects, with the most frequent genotype KIR 3DP1 (0.86) followed by 2DP1, 2DL3, 3DL1, 2DL1, 3DS1, 2DL5, 2DS4, 2DS2, 1D, 2DS5, 2DL2, 2DS1, 2DS3 and 3DP1v in leukemia successively. Compared with the control, the KIR 3DL1 (0.60) and 2DL1 (0.57) were significantly lower in the leukemia patient group than that in the control group (1.00) (P < 0.01). It is concluded that the polymorphism of KIR gene is associated with susceptibility of leukemia in Hans. There may be a negative correlation between pathogenesis of leukemia and KIR 3DL1, KIR 3DS1, KIR 2DL1, KIR 2DL5 genes.

Distinctive NK-cell receptor repertoires sustain high-level constitutive NK-cell activation in HIV-exposed uninfected individuals

We have previously associated high natural killer (NK)–cell activity and protection against HIV-1 infection in Vietnamese exposed uninfected intravascular drug users (EUs). Considering that activating and inhibitory signals sensed by NK-cell receptors regulate NK-cell activation, we performed phenotypic and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) transcript analyses of the NK-cell receptor (NKR) repertoire in 25 EUs, 19 HIV+ intravenous drug users, and 26 uninfected blood donors. Although NK-cell activation was not linked to a unique NKR repertoire in EUs, various patterns consistent with NK-cell activation were detected in EUs: high KIR3DS1/KIR3DL1 ratio associated with down-regulated KIR3DL1 transcript levels, KIR2DL3+ low-affinity receptor expansion associated to group HLA-C1 ligand in 2DS2−/2DL2− EUs, enhanced NKG2C/NKG2A ratio, and increased CD69 expression. Remarkably, EUs exhibited high constitutive degranulation activity in the absence of exogenous stimulation, as shown by the CD107a assay. Furthermore, CD161 expression was increased within the CD107a+ NK-cell compartment. Our results suggest that in response to viral exposition, particular genetic or regulated features of the NKR repertoire of EUs contribute to their high constitutive NK-cell potential. This might allow NK cells to generate a more rapid and effective immune response to HIV-1, thereby contributing to prevention toward infection.

Cutting edge: resistance to HIV-1 infection among African female sex workers is associated with inhibitory KIR in the absence of their HLA ligands

NK cells are regulated in part by killer Ig-like receptors (KIR) that interact with HLA molecules on potential target cells. KIR and HLA loci are highly polymorphic and certain KIR/HLA combinations were found to protect against HIV disease progression. We show in this study that KIR/HLA interactions also influence resistance to HIV transmission. HIV-exposed but seronegative female sex workers in Abidjan, Côte d'Ivoire, frequently possessed inhibitory KIR genes in the absence of their cognate HLA genes: KIR2DL2/KIR2DL3 heterozygosity in the absence of HLA-C1 and KIR3DL1 homozygosity in the absence of HLA-Bw4. HIV-seropositive female sex workers were characterized by corresponding inhibitory KIR/HLA pairings: KIR2DL3 homozygosity together with HLA-C1 and a trend toward KIR3DL1/HLA-Bw4 homozygosity. Absence of ligands for inhibitory KIR could lower the threshold for NK cell activation. In addition, exposed seronegatives more frequently possessed AB KIR genotypes, which contain more activating KIR. The data support an important role for NK cells and KIR/HLA interactions in antiviral immunity.

KIR haplotype content at the allele level in 77 Northern Irish families

There has been an explosion in population studies determining the frequency of KIR genes. However, there is still limited knowledge of allele and haplotype frequencies in different populations. The present study aims to determine the haplotype frequencies using allele information on ten genes and presence/absence of the other seven genes in the parents of 77 families. There were 26 of 154 different genotypes without using allele information and 143 of 154 different genotypes using allele information. These genotypes came from 96 of 308 different haplotypes. Of these, 41 were A and 55 were B. Forty-nine haplotypes occurred only once. In total, 181 (58.8%) of haplotypes were A and 127 (41.2%) were B. Three different haplotypes carried two copies of KIR2DL4, two different haplotypes were truncated with both KIR2DL4 and KIR3DL1/S1 missing, and three different haplotypes were negative for both KIR2DL2 and KIR2DL3; two of these haplotypes carried KIR2DS2. A further haplotype, present in two individuals, appeared to have two alleles of KIR2DL5A present. The percentages of individuals who were homozygous for the A haplotype, heterozygous for the A and B haplotype and homozygous for the B haplotype were 35.1%, 47.4% and 17.5% respectively. The genes KIR3DL1, KIR2DS4 and KIR2DL3 were present on 31, 32 and 15 different B haplotypes, respectively, and 64, 65 and 40 of the total B haplotypes, respectively. Sixty B haplotypes had both KIR3DL1 and KIR2DS4, and four haplotypes had KIR2DS4 and KIR2DL3. However, in 40 of 41 different and 180 of 181 total A haplotypes, KIR3DL1, KIR2DS4 and KIR2DL3 were all present (we did not allele-type for KIR2DL1 and therefore could not determine presence/absence on those haplotypes). At the allele level, homozygosity was found in 22.1%, 9.7% and 12.6% for KIR2DL4, KIR3DL2 and KIR3DL1 genes, respectively, but 62.6% and 53% for KIR2DL3 and KIR2DS4 genes, respectively, despite the fact that no one allele dominated the frequency in any of these genes.

Receptor-ligand analyses define minimal killer cell Ig-like receptor (KIR) in humans

Interactions between inhibitory killer cell immunoglobulin-like receptors (iKIR) and human leukocyte antigen (HLA) class I molecules regulate natural killer (NK) cell responses to eliminate infected and transformed cells while maintaining tolerance to healthy cells. Unlinked polymorphic gene families encode KIR receptors and HLA class I ligands and their independent segregation results in a variable number and type of iKIR + HLA pairs inherited in individuals. The diversity in the co-inheritance of iKIR + HLA pairs and activating KIR (aKIR) genes in 759 unrelated individuals from four ethnic populations was analyzed. Every individual studied inherited a minimum of one iKIR + HLA pair; suggesting that major histocompatibility complex class I-dependent inhibitory KIR signaling is essential for human NK cell function. In contrast, 13.4% of the study group lacked all aKIR genes. Twenty percent of the study group carried only one of the four iKIR + HLA pairs. Interestingly, 3% of the study group carrying only KIR2DL3 + HLA-C1 as an iKIR + HLA pair lacked aKIR genes. These data suggest that a single iKIR can constitute the minimal KIR repertoire for human NK cells. Genotypes carrying an equal number of iKIR + HLA pairs and aKIR genes represented 20% of the study group. The remaining individuals had either a dominant inhibitory KIR genotype (iKIR + HLA > aKIR) or a dominant activating KIR genotype (iKIR + HLA < aKIR). Genotypes encoding these imbalanced inhibitory and activating interactions may contribute to susceptibility or resistance to human diseases.

Study of KIR genes in tuberculosis patients

A total of 97 patients with tuberculosis (TB) and 51 controls from Xalapa, Veracruz, Mexico, were studied for the presence and absence of killer cell immunoglobulin-like receptor (KIR) genes. The number of patients with either KIR2DL1 or KIR2DL3 differed significantly compared with the controls. However, only the difference in KIR2DL3 remained significant after correction for the number of factors analysed. We also found KIR2DS2 with its presumed C1 group ligand less prevalent in TB patients than in the control group, but this result lost significance after correction.

The expression of NK cell inhibitory receptors on cytotoxic T cells in B-cell chronic lymphocytic leukaemia (B-CLL)

Immune surveillance of tumours is mediated by cytotoxic T cells (CTL) that recognise tumour antigen. Reduced reactivity of CTL towards tumour cells could thus lead to disease progression and loss of tumour control. In B-cell chronic lymphocytic leukaemia (B-CLL), the function of tumour-reactive CTL seems to correlate inversely to disease stage. Inhibitory NK cell receptors are known to suppress the CTL response upon interaction with major histocompatibility complex (MHC) class I and increased expression of such receptors on CTL may inhibit the anti-tumour response. So, the aim of this study was to investigate the expression of NK cell inhibitory receptors on CTL in B-CLL patients and if such expression correlated to disease stage. CD8+ T cells from B-CLL patients in Binet stage A (n = 26) and stage C (n = 14) and healthy controls (n = 14) were analysed for the expression of killer immunoglobulin-like receptors (KIR) CD158a (KIR2DL1), CD158b (KIR2DL2), CD158e (KIR3DL1) and the C-type lectin receptor CD94, by flow cytometry analysis. Patients with advanced disease (Binet stage C) had a significantly greater percentage of CTL expressing CD158b, CD158e and CD94 than patients with non-progressive disease (Binet stage A) and healthy controls. Stage C patients also had a significantly higher percentage of CTL expressing CD158a than stage A patients. No statistically significant differences were found between Binet A patients and healthy controls. Our results suggest that increased expression of KIR and CD94 on CTL in advanced stage B-CLL may potentially contribute to the impaired anti-tumour immune response in these patients.

Analysis of KIR2D receptors on peripheral blood lymphocytes from liver graft recipients

KIR2D receptors are killer cell immunoglobulin-like receptors (KIRs) specific for HLA-C epitopes, that are expressed on NK cells as well as on minor peripheral blood T-cell subsets, and are able to control NK and T cells activity. The present work explores NK, and particularly CD8(+) T cells expressing KIR2D2L1/S1 (CD158a) or KIR2D2L2/3/S2 (CD158b) receptors in liver graft alloresponse. Flow cytometry was used to analyse peripheral blood mononuclear cells stained with anti-CD158a and anti-CD158b antibodies from 110 liver recipients and 46 healthy controls, previous to and along the first month after transplantation. Pre-transplantation data shows that both CD158a and CD158b molecules can be detected on NK and T cells from all patients and controls, but both KIR2D(+)NK cells are significantly under-represented in patients respect to controls (P<0.001), and CD3(+)CD8(+)CD158a(+) cells decreased particularly in patients suffering from acute rejection (4.03+/-1.33 cells/microL) compared with controls (7.8+/-2.4 cells/microL). Following transplantation, KIR2D(+)CD8(+) T-cell repertoires increased through the first month, mainly in recipients with a good graft acceptance. In summary, monitoring of KIR2D(+)CD8(+) T cells, particularly KIR2DL1/S1(+)CD8(+) T cells at pre-transplant, and both KIR2DL1/S1(+) and KIR2DL2/3/S2(+) T-cell subsets at early post-transplant period, could offer useful information for clinical follow-up of liver grafts.

Killer Ig-like receptor (KIR) genotype and HLA ligand combinations in ulcerative colitis susceptibility

Killer immunoglobulin-like receptors (KIRs) are expressed on natural killer cells and some T-cell subsets and produce either activation or inhibitory signals upon binding with the appropriate human leucocyte antigen (HLA) ligand on target cells. Recent genetic association studies have implicated KIR genotype in the development of several inflammatory conditions. Ulcerative colitis (UC) is an inflammatory disorder of the colonic mucosa that results from an inappropriate activation of the immune system driven by host bacterial flora. We developed a polymerase chain reaction-sequence specific primer (SSP)-based assay to genotype 194 UC patients and 216 control individuals for 14 KIR genes, the HLA-Cw ligand epitopes of the KIR2D receptors and a polymorphism of the lectin-like-activating receptor NKG2D. Initial analysis found the phenotype frequency of KIR2DL2 and -2DS2 to be significantly increased in the UC cohort (P=0.030 and 0.038, respectively). Logistic regression analysis revealed a protective effect conferred by KIR2DL3 in the presence of its ligand HLA-Cw group 1 (P=0.019). These results suggest that KIR genotype and HLA ligand interaction may contribute to the genetic susceptibility of UC.

Nature of allelic sequence polymorphism at the KIR3DL3 locus

KIR3DL3 is a framework gene of the Leukocyte Receptor Complex, present in all individuals and haplotypes analysed to date. We describe 17 novel KIR3DL3 alleles, including seven single nucleotide polymorphic (SNP) positions within the coding region. Sequence variation within introns included a VNTR within intron 1. As KIR3DL3 mRNA is known to be expressed in decidual NK cells, we investigated the impact of KIR3DL3 allelic variation on pre-eclampsia. No statistical difference in allele frequency or polymorphism was observed between pre-eclampsia patient and control cohorts. Linkage disequilibrium (LD) analysis of exonic SNPs suggested that recombination may be a mechanism of generating sequence diversity within KIR3DL3. A potential recombination hotspot was located within intron 5. A strong LD was detected between polymorphism in exon 6 of KIR3DL3 and the KIR gene -2DL3 or -2DS2 loci, which define the centromeric end of two main haplotypes (A and B) of the KIR cluster. Comparison of primate KIR sequences indicated that the Ig domains of KIR3DL3 are highly conserved between chimpanzee, gorilla and humans. Investigation of KIR3DL3 dN/dS ratios indicated a greater level of synonymous mutations consistent with purifying selection, although positive selection was detected acting on two sites within the stem region.

Diversity of killer cell immunoglobulin-like receptor genes in Pacific Islands populations

Killer immunoglobulin-like receptors (KIRs) regulate the activity of NK and T cells through interaction with specific HLA class I molecules on target cells. To date, 16 KIR genes and pseudogenes have been identified. Diversity in KIR gene content and KIR allelic and haplotype polymorphism has been observed between different ethnic groups. Here, we present data on the KIR gene distribution in Pacific Islands populations. Sixteen KIR genes were observed in Pacific Islands populations from the Cook Islands, Samoa, Tokelau, and Tonga. The majority of KIR genes were present at similar frequencies between the four populations with KIR2DL4, KIR3DL2, and KIR3DP1 genes observed in all individuals. Commonly observed KIR genes in Pacific Islands populations (pooled frequencies) were KIR2DL1 (0.77), KIR2DL3 (0.77), KIR3DL1 (0.65), KIR3DL3 (0.93), KIR2DS4/1D (0.78), and KIR2DP1 (0.82), compared to the less-frequently observed KIR2DL2 (0.27), KIR2DL5 (0.30), KIR2DS1 (0.19), KIR2DS2 (0.27), KIR2DS3 (0.16), KIR2DS5 (0.17), and KIR3DS1 (0.18) genes. Differences in KIR gene frequency distributions were observed between the Pacific Islands populations and when compared to other populations. Sixty-nine different genotypes were identified, with five genotypes accounting for more then 50% of all genotypes observed. The number of genotypes observed in each population was similar in the Cook Islands, Samoan, and Tokelauan populations (19, 18, and 19, respectively), but 26 different genotypes were observed in Tongans. The putative haplotype A was predominantly observed over haplotype B in all Pacific Islands populations. Significant linkage disequilibrium was observed for a number of KIR gene pairs.

Increased expression of the natural killer cell inhibitory receptor CD94/NKG2A and CD158b on circulating and lesional T cells in patients with chronic plaque psoriasis

BACKGROUND

Psoriasis is a common inflammatory cutaneous disorder characterized by activated T-cell infiltration. T lymphocytes bearing natural killer cell receptors (NKRs) have been suggested to play an important role in the pathogenesis of psoriasis. However, the expression pattern of activating and inhibitory NKRs on T lymphocytes from psoriatic patients and its significance in psoriasis needs further study.

OBJECTIVES

To investigate the pathogenesis of NKR-expressing T cells in psoriasis.

MATERIALS AND METHODS

Thirty patients with chronic plaque psoriasis and 20 healthy controls were enrolled in this study. The immunophenotypic profiles of NKRs, including CD56, CD16 (activating NKRs), CD158a, CD158b, CD94 and NKG2A (inhibitory NKRs), were analysed in peripheral blood T lymphocytes, as well as psoriatic lesional infiltrating T cells, by triple-fluorescence flow cytometry.

RESULTS

A significant increase of inhibitory CD8+ CD158b+, CD4 CD8 CD158b+ and CD8+ CD94/NKG2A+ T cells was found in the peripheral blood of patients with psoriasis when compared with controls. Tissue-infiltrating T lymphocytes expressing inhibitory receptors CD158b, CD94 and NKG2A were found in psoriatic lesions. There was a significant positive correlation between the increased percentage of circulating CD8+ CD94/NKG2A+ T cells and the Psoriasis Area and Severity Index.

CONCLUSIONS

In the present study, we demonstrated increased proportions of particular subsets of inhibitory CD158b+ and/or CD94/NKG2A+ T cells in patients with psoriasis. The elevation of these inhibitory NKR-expressing T cells was correlated with disease severity, which may signify the possibility of chronic antigen-driven stimulation and dysregulated cytokine production in the pathogenesis of psoriasis.

KIR gene in ethnic and Mestizo populations from Mexico

Killer cell immunoglobulin-like receptors are characterized by their great diversity of genes and alleles. Population studies have identified the presence of a broad variety of genotypes. In Mexico, there are diverse ethnic groups representing 9% of the total population and the rest is composed of Mestizos with a more varied biology. For the purpose of this study, genotyping was performed in Mestizos, in Mexico City inhabitants, and in three ethnic groups. The frequencies of genes KIR2DL2, 2DL5, 2DS1-3, 2DS5, and 3DS1 showed a greater variability in the groups studied. A total of 12 different genotypes were identified, the higher number for the Mestizos and the lower number for the Tarahumaras. Genotype 1 was found at a greater frequency in all the groups, except for the Tarahumaras, in which genotype 4 was more frequent. The frequency of genotypes 4 and 8 in Mexicans was higher than that for other populations analyzed. By subtyping of KIR3DL1, 3DL2, 2DL1, and 2DL3, two B haplotypes were identified in families; both were absent in Caucasian families. Our results indicated a greater diversity of genes in the Mestizos group than in the ethnic groups.

Activating killer cell immunoglobulin-like receptor gene KIR2DS1 is associated with psoriatic arthritis

Killer cell immunoglobulin-like receptor genotyping was performed on a cohort of American Caucasian patients with psoriasis to investigate any possible relationship between these chromosome 19 genes and autoimmune-linked disease. This patient cohort also contained a subgroup of patients who had been additionally diagnosed as positive for psoriatic arthritis (PsA). Because of the known association of human leucocyte antigen (HLA)-Cw*06 with psoriasis, the study concentrated on the five KIR genes that have HLA-C as their recognized ligand (i.e., KIR2DL1, -2DL2, -2DL3, -2DS1, and -2DS2). An increase in the frequency of the activating KIR2DS1 gene was detected in the PsA patients, compared with psoriasis patients negative for PsA and an unaffected American Caucasian control group.

T-cell large granular lymphocyte leukemias have multiple phenotypic abnormalities involving pan-T-cell antigens and receptors for MHC molecules

T-cell large granular lymphocyte (T-LGL) leukemias represent monoclonal T-cell expansions that express CD16, CD56, or CD57 and cause cytopenias. The identification of T-LGL leukemias can be difficult because reactive T-LGL cells also can express CD16, CD56, and CD57, and many leukemia cases show only mild lymphocytoses. In this study, 23 T-LGL leukemia cases were analyzed by 3- and 4-color flow cytometry to identify markers that could aid in discriminating leukemic from normal T-LGL. In most cases (18/23), abnormalities (bright, dim, or negative expression) of 2 or more pan-T-cell antigens were identified, with all cases showing abnormal CD5 levels. Abnormal expression of CD94 was identified in 22 of 23 cases, and 15 of 21 cases also showed abnormal expression of class 1 MHC receptor molecules identified by antibodies against CD158a, CD158b, CD158e, CD158i, CD158k, and CD94. These studies help define abnormal phenotypic features typical of T-LGL leukemia that may have important diagnostic value.

The inhibitory receptor IRp60 (CD300a) suppresses the effects of IL-5, GM-CSF, and eotaxin on human peripheral blood eosinophils

Allergic, inflammatory, and immune responses carried out by eosinophils are regulated by the cross talk between activatory and inhibitory signals. While much data has been obtained on activatory signals, inhibitory receptors on these cells have received scant attention. Therefore, we screened the surface of human peripheral blood eosinophils for inhibitory receptors using monoclonal antibodies (mAbs) previously generated to recognize receptors on human natural killer cells. Eosinophils from all of the donors examined expressed the inhibitory receptors IRp60, LIR3/ILT5, FcgammaRIIB, and p75/AIRM but not LIR1/ILT2, p58.1, p58.2, p70, or NKG2A/CD94 (n = 15). Interestingly, 25% of the donors expressed p140. IRp60 cross-linking inhibited eotaxin-dependent transmigration of eosinophils in a calcium-independent fashion. In addition, cross-linking of IRp60 on the eosinophils in the presence of IL-5/GM-CSF inhibited the antiapoptotic effect of these cytokines and blocked the release of TNF-alpha, IL-1beta, IFN-gamma, IL-4, and 3T3 fibroblast proliferation. Cross-linking of IRp60 inhibited IL-5-mediated JAK2 phosphorylation as well as eotaxin- and IL-5/GM-CSF-mediated ERK1/2 and p38 phosphorylation. Furthermore, upon cross-linking, IRp60 underwent tyrosine phosphorylation and recruited SHP-1 but not SHP-2. These findings demonstrate a novel pathway for suppressing the activity of human eosinophils, thus indicating IRp60 as a future potential target for the treatment of allergic and eosinophil-associated diseases.

A population-based cohort study of KIR genes and genotypes in relation to cervical intraepithelial neoplasia

Natural killer (NK) cells are involved both in control of virus infections and in elimination of tumor cells. Killer immunoglobulin-like receptors (KIRs) either activate or inhibit NK cell-mediated cytolysis, protecting healthy cells from destruction while enabling killing of abnormal cells. To investigate whether KIR genes or genotypes are associated with cervical carcinogenesis, a nested case-control study of 65 case women with cervical intraepithelial neoplasia (CIN) diagnosed during a 6-year follow-up of 15,234 women and 150 control women from the same cohort that remained healthy was performed. More than 70 different genotypes were observed, and 33 of which had not been described previously. An A-genotype including KIR2DL1, KIR2DL2, KIR2DL3, KIR2DL4, KIR3DL1, KIR3DL2, KIR3DL3, and KIR2DS4 was associated with increased risk of CIN (OR 6.7; 95% CI 1.7-26.3), and KIR2DL5B*002 appeared to have an inverse association with disease (OR 0.5; 95% CI 0.5-2.9). There was no association of CIN with the number of activating KIR genes. There was also no association between KIR genes and type of human papilloma virus or with other CIN-related immune response genes. It was concluded that certain KIR genes and genotypes may associate with cervical neoplasia.

Expression of MHC class I receptors confers functional intraclonal heterogeneity to a reactive expansion of gammadelta T cells

NK cell receptors for MHC class I molecules (MHC-NKR) can be expressed by T cell subsets. The restricted repertoire and phenotypic characteristics of MHC-NKR(+) T cells indicate that expression of MHC-NKR is acquired upon antigenic challenge and might promote expansion of T cells. Previous studies performed on in vitro generated alphabeta T cell clones concluded that MHC-NKR expression was not a clonal attribute. Here, we examined a massive monoclonal expansion of a non-leukemic gammadelta T cell population found in the peripheral blood of a lung-transplanted patient who suffered from a cytomegalovirus infection. Despite their monoclonality, these T cells displayed a heterogeneous and stable in vivo Ig- and lectin-like MHC-NKR phenotype. Twenty percent of the cells displayed a CD94(+)NKG2A(+) phenotype, and 10% were labeled with an anti-CD158b1/b2/j monoclonal antibody. A CD158b/j(+) gammadelta T cell clone derived in vitro from patient's peripheral blood lymphocytes was shown to express the activating form CD158j (KIR2DS2), which once cross-linked stimulated the clone cytolytic function and costimulated the TCR-induced production of cytokines, independently of the killer-activating receptor-associated protein (KARAP). In conclusion, heterogeneity of MHC-NKR expression confers a functional intraclonal diversity that may participate to induction of specific gammadelta T cell effector functions or proliferation upon pathogen challenge.

Comparison of killer Ig-like receptor genotyping and phenotyping for selection of allogeneic blood stem cell donors

The repertoire of killer Ig-like receptors (KIRs) can be determined at the level of DNA, RNA, or surface protein expression for selection of blood stem cell donors. We compared genotyping and phenotyping of the four inhibitory KIRs that are important in transplantation for leukemia in 73 unrelated persons. In 5 (7%) of the 68 individuals in whom the KIR2DL1 gene was present and in 10 (15%) of the 67 in whom KIR3DL1 was present, the corresponding receptor was not expressed by NK cells, as determined by flow cytometry analysis. In contrast, one or both allelic forms of KIR2DL2/KIR2DL3 were expressed by a high proportion of NK cells in all 73 individuals. However if both KIR2DL2 and KIR2DL3 genes were present, KIR2DL3 was preferentially expressed, as transcripts of KIR2DL2 was not detectable by RT-PCR in 42% of these individuals. In total, repertoire assessment for the four KIRs by genotyping vs phenotyping was not in complete agreement in 18 (25%) of the 73 individuals. Furthermore, among the samples that tested positive for the expression of a certain KIR gene, the levels of transcripts and surface expression varied considerably as measured by both real-time quantitative PCR and flow cytometry analysis. Extension of this comparative analysis to include all 12 KIR family members showed that KIR2DL3 and KIR3DL2 were the only genes whose transcripts were consistently detectable. These results caution the use of genotyping alone for donor selection or leukemia-relapse prognostication because some KIRs may be expressed at a very low level.

Expression of Killer Immunoglobulin-like Receptors on Peripheral Blood NK Cell Subsets of Women with Recurrent Spontaneous Abortions or Implantation Failures

PROBLEM

Decidual natural killer (NK) cells express inhibitory receptors (killer immunoglobulin-like receptors, KIRs), which bind to ligands on trophoblast cells (human leucocyte antigen, HLA-C). This interaction appears to block NK cytotoxicity against trophoblast cells. In this study, we investigated the expression of inhibitory and activating receptors in peripheral blood NK cells of women with recurrent spontaneous abortion (RSA) or implantation failures.

METHOD OF STUDY

CD56(dim)/CD16(+), CD56(bright)/CD16(-) NK cells and CD56(+)/CD3(+) NKT cells of women with RSA or in vitro fertilization (IVF) failures and normal controls were analyzed for the expression of CD158a, CD158b inhibitory KIRs or CD161-activating receptors, by flow cytometric analysis.

RESULTS

CD158a and CD158b inhibitory receptor expression by CD56(dim)/CD16(+) and CD56(bright)/CD16(-) NK cells were significantly decreased, and CD161-activating receptor expression by CD56(+)/CD3(+) NKT cells was significantly increased in women with implantation failures when compared with normal controls.

CONCLUSIONS

An imbalance between inhibitory and activating receptor expression was found in NK cells of women with implantation failures. This imbalance may explain the adverse reproductive outcome.

Human leucocyte antigen class I and killer immunoglobulin-like receptor expression patterns in T-cell large granular lymphocyte leukaemia

T-cell large granular lymphocyte leukaemia (T-LGLL) is often associated with suppression of haematopoiesis through unknown mechanisms. Killer immunoglobulin-like receptors (KIRs) binding human-leucocyte antigen (HLA)-I in an allele-specific manner are frequently expressed by T-LGLL cells. HLA-I genotyping was performed in seven T-LGLL cases in which the neoplastic cells were known to express a single KIR isoform (CD158a, CD158b or CD158e). Five cases showed absence of the cognate HLA-I antigen for the expressed KIR isoform, resulting in KIR/HLA-I 'mismatch'. Cytopenias occurred in all five 'mismatch' patients but not in two patients with 'match', suggesting that KIR/HLA-I mismatch may contribute to the suppression of haematopoiesis.

Three Structurally and Functionally Divergent Kinds of Promoters Regulate Expression of Clonally Distributed Killer Cell Ig-Like Receptors (KIR), of KIR2DL4, and of KIR3DL3

The generation of killer cell Ig-like receptor (KIR) expression patterns in NK cells involves variegated silencing of KIR genes by DNA methylation. To identify regulatory elements involved in KIR gene activation, upstream regions of KIR genes were functionally characterized in NK3.3 cells as well as in primary NK cells. Three kinds of KIR promoters were defined, controlling clonally expressed KIR genes, the constitutively active KIR2DL4, and the weakly expressed KIR3DL3. Upstream of a short core promoter common to all KIR genes, a region containing functionally divergent elements was characterized. Although this region had no impact on the activity of the KIR2DL3 promoter, an inhibitory element was identified in the KIR2DL4 promoter and an activating element was found in the KIR3DL3 promoter. Upon treatment with a methyltransferase inhibitor, KIR3DL3 expression could be readily induced showing that the low levels of KIR3DL3 expression in peripheral blood are due to sustained DNA methylation of an otherwise fully functional promoter. Analysis of transcription factor binding sites identified a functional acute myeloid leukemia (AML) site common to all three KIR promoters. Mutation of this site led to a substantial increase in activity of all KIR promoters. Among the different members of the AML family, AML-2 was identified as the predominant KIR binding factor. The present study suggests that AML-2 acts as a repressor of KIR expression in mature NK cells and opens the possibility that AML factors and associated cofactors are involved in regulation of KIR expression during NK cell development.

Expression of CD158b on Peripheral Blood Lymphocytic Cell After Kidney Transplantation

OBJECTIVE

To investigate the expression of CD158b on peripheral blood lymphocytes after kidney transplantation.

METHODS

Sixty two kidney transplant patients were divided into two groups (normal group and rejection group) according to pathologic results and clinical situation. Blood samples were assessed for percentage of CD3+; CD19+; CD3-CD16/56+; CD3+CD158b+; CD19+CD158b+, and CD3-CD16/56+CD158b+ subsets.

RESULTS

The percentages of CD3+ cells preop as well as at 1 and 7 postoperative and the day acute rejection happened were 60.06 +/- 4.67, 40.43 +/- 4.11, 31.67 +/- 4.04, and 39.21 +/- 5.20, respectively. The percentages of CD3-CD16/56+ were 21.65 +/- 1.79, 33.84 +/- 5.45, 38.10 +/- 4.86, and 39.53 +/- 4.80, respectively. The percentages of CD3+CD158b+ were 1.46 +/- 0.31, 1.88 +/- 0.70, 2.03 +/- 1.04, and 0.65 +/- 0.12, respectively. The percentages of CD3-CD16/56+CD158b+ were 5.87 +/- 1.24, 3.57 +/- 0.57, 2.82 +/- 0.45, and 1.60 +/- 0.33, respectively.

CONCLUSIONS

The percentage of CD3+ cells in the normal and the rejection groups decreased significantly. The percentages of CD158b+T cells decreased significantly after acute rejection. The percentage of CD158b+NK cells decreased significantly after kidney transplantation, decreasing gradually after acute rejection. The percentage of CD158b+ total T cells decreased significantly following acute rejection. The percentage of CD3-CD16/56+CD158b+ of total NK cells decreased significantly after kidney transplantation and after acute rejection. Because few factors interfere with the expression of CD158b on NK cells, monitoring of this marker may be accurate and sensitive.

Expression of inhibitory KIR is confined to CD8+ effector T cells and limits their proliferative capacity

A subset of effector/memory CD8(+) T cells expresses natural killer cell receptors (NKR). Expression of inhibitory NKR at that stage of T cell differentiation is poorly understood. Interestingly, recent studies in mice indicated that transgenic expression of an inhibitory NKR induced the accumulation of memory T cells by inhibiting activation-induced cell death (AICD). To further understand the role of inhibitory NKR on T cells, we characterized the subset of human peripheral T cells expressing the inhibitory NKR, CD158b, and studied the modulation of antigen-driven T cell expansion by an endogenous inhibitory NKR. We found that CD158b expression was confined to a population of CD8(+)TCRalphabeta(+) effector T cells as defined by a CD45RA(+)CCR7(-) phenotype and high constitutive expression of granzyme B1. Few cells expressed the activating form CD158j in the absence of CD158b. Functionally, engagement of CD158b by MHC ligands diminished early TCR signaling, as well as AICD. However, the reduced AICD did not rescue cells for proliferation, since T cell expansion in the presence of CD158b triggering was impaired. Expression of inhibitory NKR on effector CD8(+) T cells may explain in part the poor replicative capacity of T cells at that stage of differentiation.

Genetic polymorphism of NK receptors and their ligands in melanoma patients: prevalence of inhibitory over activating signals

Antitumor cytotoxicity of NK cells and T cells expressing NK-associated receptors is regulated by interaction between their cell surface killer immunoglobulin-like receptors (KIRs) and CD94/NKG2 heterodimers with MHC class I ligands on target cells. To test the hypothesis that KIR and/or HLA polymorphisms, and KIR/HLA combinations could contribute to the tumorigenesis, association studies were performed in 50 patients with malignant melanoma (MM) in different stages of disease and 54 controls. Our data showed that the frequency of inhibitory and activating KIR genes and KIR genotypes did not differ significantly between healthy individuals and melanoma patients. HLA haplotype distribution showed statistically significant increased frequencies of A*01-B*35-Cw*04 (0.069 vs 0.000; pc < 0.05; OR = 19.9), A*01-B*08-DRB1*03 (0.079 vs 0.019; pc < 0.05; OR = 4.5), and A*24-B*40-DRB1*11 (0.026 vs 0.000; pc < 0.05; OR = 7.1) in melanoma patients compared with healthy controls. Individuals homozygous for group 2 HLA-C ligands were less frequent in the patient group compared with the control cohort (12% vs 31.5%; p < 0.017). In addition, we observed an increased frequency (88.0% vs 68.5%; p = 0.017; OR = 2.80) of KIR2DL2/2DL3 in combination with their group 1 HLA-C ligands, while the presence of these KIRs in the absence of the putative ligands was decreased (12.0% vs 31.5%; p = 0.017) in the patient group. Furthermore, an increased frequency of activating KIR2DS1 in the absence of the putative HLA-C(Lys80) ligands was found in melanoma patients (16.0% vs 9.2%). In contrast, KIR2DS2 was absent in patients more often (38.0% vs 25.9%) when the presumptive HLA-C(Asn80) ligands were present. A slightly higher incidence of KIR3DL1 in combination with the less effective Bw4(Thr80) ligands was seen in patients with primary (20.8%) compared with metastatic (4.2%) disease. The data obtained in this study imply that there may not be a direct association between KIR gene content in the genome and the presence of malignant melanoma, or melanoma progression. However, some HLA haplotypes could be predisposing to MM in the Bulgarian population. Furthermore, distinct KIR/HLA ligand combinations may be relevant to the development of malignancy whereby inhibition overrides activation of NK cells and T cells expressing NK-associated receptors, which in turn might facilitate tumor escape and progression.

Investigation of killer cell immunoglobulin-like receptor gene diversity III. KIR2DL3

The allelic variation of one of the chromosome 19 KIR genes, KIR2DL3, has been investigated using a polymerase chain reaction sequence-specific oligonucleotide probe-based methodology. The procedure has been applied to a healthy Northern Irish control group in order to establish phenotype and genotype frequencies in this Caucasian population. In addition, cell line DNA and Centre d'Etude du Humaine (CEPH) families, both from the 13th International Histocompatibility Workshop have been investigated, establishing control data for this gene.

[Killer immunoglobulin-like receptor gene distribution in Guangdong Han population]

OBJECTIVE

To investigate the distribution of killer immunoglobulin-like receptor (KIR) gene in Guangdong Han population.

METHODS

KIR phenotype was examined by PCR with sequence-specific primers in 96 subjects of Han nationality in Guangdong Province of China, and KIR frequency was calculated and compared with those in Caucasian, north Indian and Japanese populations.

RESULT

The gene expression frequency of KIR in Guangdong Han people was 2DL1(0.85), 2DL2(0.12), 2DL3(0.58), 2DL4(1), 2DL5(0.24), 3DL1(0.96), 3DL2(1), 3DL3(1), 2DP1(0.97), 2DP2(0.98), 2DS1(0.10), 2DS2(0.30), 2DS3(0.02), 2DS4(0.28), 1D(0.65), 2DS5(0.19), and 3DS1(0.23) respectively. Comparison of the KIR recognizing the same HLA ligand suggested significantly higher expression frequency of inhibitory KIR than that of activating KIR. Compared with Caucasian and north Indian populations, Guangdong Han population had significantly lower expression frequency of activating KIR gene with the exception of KIR2DS4.

CONCLUSION

Different KIR genes have different expression frequencies in Guangdong Han population, and KIR gene distribution varies between populations of different races.

Cutting edge: engagement of CD160 by its HLA-C physiological ligand triggers a unique cytokine profile secretion in the cytotoxic peripheral blood NK cell subset

CD160 is an Ig-like activating NK cell receptor expressed on the majority of circulating NK cells. This population corresponds to the nonproliferating, highly cytolytic, CD56dimCD16+ subset. CD160 engagement by HLA-C molecules mediates cytotoxic function. In this study, we report that upon specific activation by the physiological ligand HLA-C, or Ab cross-linking, CD160+ peripheral blood NK cells produce IFN-gamma, TNF-alpha, and IL-6. This unique CD160-mediated cytokine production differs from the one observed after CD16 engagement whose expression is also restricted to the CD56dim cytotoxic NK cell subset. As already reported for the CD160-mediated cytotoxic effector function, CD160-mediated cytokine production by peripheral blood-NK cells is negatively controlled by the killer Ig-like receptor CD158b. Thus, the CD160 receptor represents a unique triggering surface molecule expressed by cytotoxic NK cells that participates in the inflammatory response and determines the type of subsequent specific immunity.

Comparative analysis of NK cell subset distribution in normal and lymphoproliferative disease of granular lymphocyte conditions

We have characterized the heterogeneity of human blood NK cell subsets defined by expression of KIR, lectin like receptors and NK cell differentiation markers within a cohort of 51 healthy Caucasian individuals. High inter-individual variability in cell surface expression of most NK cell markers is observed. Range values defining NK cell subsets in healthy donors were further used as references to characterize 14 patients with NK-type lymphoproliferative disease of granular lymphocytes (NK-LDGL). Alterations of the KIR repertoire were noted in all NK-LDGL patients. NK cell expansions were classified as oligoclonal KIR(+) or as non-detectable KIR ((nd)KIR) using anti-KIR2DL1/2DS1, anti-KIR2DL2/2DL3/2DS2, anti-KIR3DL1 and anti-KIR2DS4 monoclonal antibodies. A major reduction in the size of the CD56(bright) NK cell subset was a constant feature of NK-LDGL. Altered distribution of CD94(+), CD161(+), and CD162R(+) NK cell subsets was also observed in NK-LDGL patients. Considering the potential role of NK cells in eliminating tumors or virus-infected cells, the reference values defined in this study should be valuable to characterize both quantitative and qualitative alterations of the NK cell repertoire in pathological conditions and to monitor NK cell reconstitution following hematopoietic transplantation.

Ligand binding to inhibitory killer cell Ig-like receptors induce colocalization with Src homology domain 2-containing protein tyrosine phosphatase 1 and interruption of ongoing activation signals

Interaction of NK cells with target cells leads to formation of an immunological synapse (IS) at the contact site. NK cells form two distinctly different IS, the inhibitory NK cell IS (NKIS) and the cytolytic NKIS. Cognate ligand binding is sufficient to induce clustering of inhibitory killer cell Ig-like receptors (KIR) and phosphorylation of both the receptor and the phosphatase Src homology domain 2-containing protein tyrosine phosphatase 1 (SHP-1). Recruitment and activation of SHP-1 by a signaling competent inhibitory receptor are essential early events for NK cell inhibition. We have in the present study used three-dimensional immunofluorescence microscopy to analyze distribution of inhibitory KIR, SHP-1, LFA-1, and lipid rafts within the NKIS during cytolytic and noncytolytic interactions. NK clones retrovirally transduced with the inhibitory KIR2DL3 gene fused to GFP demonstrate colocalization of KIR2DL3 with SHP-1 in the center of early inhibitory NKIS. Ligand binding translocates the receptor to the center of the IS where activation signals are accumulating and provides a docking site for SHP-1. SHP-1 and rafts cluster in the center of early inhibitory NKIS and late cytolytic NKIS, and whereas rafts continue to increase in size in cytolytic conjugates, they are rapidly dissolved in inhibitory conjugates. Furthermore, rafts are essential only for cytolytic, not for inhibitory, outcome. These results indicate that the outcome of NK cell-target cell interactions is dictated by early quantitative differences in cumulative activating and inhibitory signals.

Decrease in a specific killer cell immunoglobulin-like receptor on peripheral natural killer cells in women with recurrent spontaneous abortion of unexplained etiology

PROBLEM

The aim of this study was to investigate immunophenotypic characteristics of natural killer (NK) cells by assessing specific molecules expressed in women with recurrent spontaneous abortion (RSA) of unexplained etiology.

METHOD OF STUDY

Peripheral blood cells were obtained from 20 RSA women and 15 fertile controls. The expression of perforin, CD94, CD161, CD158a, CD158b, and CD244 on CD3- CD56+ NK cells was analyzed by flow cytometry.

RESULTS

A significant decrease in CD158a expression was demonstrated in RSA women (mean +/- SD, 22.9 +/- 8.7%) as compared with that in controls (33.6 +/- 15.7%) (P < 0.05). The percentage of NK cells showing dual expression of CD94 and CD161 was relatively higher in RSA women (55.1 +/- 10.2%) than in the controls (47.1 +/- 19.0%), but without statistically significant (P = 0.096). The expression of perforin, CD158b, or CD244 in RSA women did not differ from that in the controls.

CONCLUSIONS

A divergence of the specific NK cell repertoire might be related to the etiology of RSA.

Isolation of a novel KIR2DL3-specific mAb: comparative analysis of the surface distribution and function of KIR2DL2, KIR2DL3 and KIR2DS2

In recent years an increasing number of sequences coding for new KIRs have been described. However, the limited availability of mAbs with unique KIR specificities has hindered an exhaustive assessment of their actual function, HLA-specificity, expression at the cell surface and distribution in different cell populations. In this study we report the generation of a novel mAb (ECM41) specific for KIR2DL3 molecules. By the use of cell transfectants expressing one or other KIR we show that this reagent allows discrimination of KIR2DL3 from other GL183 mAb-reactive molecules such as KIR2DL2 and KIR2DS2. Moreover we show that this novel mAb can be used to assess the surface expression and distribution of KIR2DL3 in different polyclonal NK populations and in NK cell clones. Along this line, we were able to analyze the HLA class I specificity of NK clones expressing either KIR2DL3 or KIR2DL2, two inhibitory receptors that were so far serologically undistinguishable. Finally, the combined use of GL183 and ECM41 mAbs in redirected killing assays allowed us to investigate the functional outcome of the simultaneous engagement of KIR2DL3 and KIR2DS2 in NK cell clones co-expressing KIRs that display opposite (inhibitory vs activating) function.

HLA and NK Cell Inhibitory Receptor Genes in Resolving Hepatitis C Virus Infection

Natural killer (NK) cells provide a central defense against viral infection by using inhibitory and activation receptors for major histocompatibility complex class I molecules as a means of controlling their activity. We show that genes encoding the inhibitory NK cell receptor KIR2DL3 and its human leukocyte antigen C group 1 (HLA-C1) ligand directly influence resolution of hepatitis C virus (HCV) infection. This effect was observed in Caucasians and African Americans with expected low infectious doses of HCV but not in those with high-dose exposure, in whom the innate immune response is likely overwhelmed. The data strongly suggest that inhibitory NK cell interactions are important in determining antiviral immunity and that diminished inhibitory responses confer protection against HCV.

Distribution of killer cell immunoglobulin-like receptors in the Greek population

The interaction between killer cell immunoglobulin-like receptors (KIR) expressed on natural killer (NK) cells, and human leukocyt antigen (HLA) molecules expressed on target cells is known to regulate the cytolytic activity. A wide range of KIR genotypes is observed in the population, as the number of KIR loci can vary. In the present study we have determined the frequencies and combinations of 13 KIR genes and two CD94:NKG2 receptor genes and their distribution in the two haplotype groups in a panel of 233 unrelated healthy Greek Caucasians. We have typed genomic DNA for the presence of the putative KIR loci KIR2DL1, KIR2DL2, KIR2DL3, KIR2DL4, KIR3DL1, KIR3DL2, KIR3DL3, KIR2DS1, KIR2DS2, KIR2DS3, KIR2DS4, KIR2DS5, and KIR3DS1 using modified polymerase chain reaction sequence-specific primers. The frequency of KIR loci combined with the linkage disequilibrium values suggest that the Greek population shares several general features with other Caucasoid populations studied before, but still distinguishes itself by the increased or decreased frequency of several alleles. The majority of the 45 different KIR genotypes seen in Greeks have been observed in Caucasoid populations studied before. Nevertheless, two of these genotypes, although met in other populations, have not been found in Caucasians before. One individual possesses a novel profile with no KIR inhibitory gene. The A haplotypes remain the most prevalent, with AA1 being the most common genotype, and the number of inhibitory KIRs being more variable than the number of noninhibitory KIRs in most haplotypes.

Abnormal killer inhibitory receptor expression on natural killer cells in patients with Behçet's disease

Viral infection has been assigned some role in the pathogenesis of Behçet's disease (BD). Defects in natural killer (NK) cell repertoire may be involved in impaired antiviral immunity, leading to the development of BD. We studied killer inhibitory receptor (KIR) expression in 40 patients with BD. CD94 and CD158b expression of NK cells was normal in a great majority of BD patients. NKB1 expression was reduced in eight and increased in six. Twelve of these 14 patients (86%) had severe eye disease. Some had reduced NKB1 and enhanced CD158a expression simultaneously, or enhanced NKB1 and reduced CD158a simultaneously, suggesting a skewed NK cell repertoire in BD. Collectively, KIR expression was abnormal in the BD patients with severe eye disease. This may result from genetic predisposition, or certain viruses may affect the KIR repertoire formation in BD patients. Abnormal KIR expression of NK cells may be associated with the development of BD.

The involvement of natural killer cells in the pathogenesis of severe acute respiratory syndrome

By using peripheral blood samples from 221 cases of severe acute respiratory syndrome (SARS), 34 of Mycoplasma pneumoniae infection, and 44 healthy adults, we measured the total number of natural killer (NK) and CD158b+ NK cells (CD158b+ NK) using flow cytometric analysis and calculated the percentage of CD158b+ NK cells. The total number of NK and CD158b+ NK cells and the percentage of CD158b+ NK cells were significantly lower in patients with SARS than in those with M. pneumoniae infection (P < .05 for all) and healthy subjects (P < .01, P < .01, P < .05, respectively); in 72 patients with severe SARS than in 149 with mild SARS (P < .05 for all); and in 174 cases of SARS with anti-SARS coronavirus-specific IgG and/or IgM antibodies than in 47 without antibodies (P < .05, P < .01, P < .01, respectively). There were no significant differences for the 3 values among patients with SARS without anti-SARS coronavirus antibody, patients with M. pneumoniae infection, and healthy subjects. The number of NK cells and the expression of CD158b on the surface of NK cells changed in patients with SARS and correlated with disease severity and the presence of anti-SARS coronavirus-specific antibodies; SARS differed from M. pneumoniae infection in pathogenesis involving NK cells. Monitoring the total number of NK and CD158b+ NK cells and the percentage of CDD158b+ NK cells might aid in differentiating SARS from M. pneumoniae infection.

Differential expression of KIR/NKAT2 and CD94 molecules on decidual and peripheral blood CD56bright and CD56dim natural killer cell subsets

OBJECTIVE

To investigate killer inhibitory receptor (KIR) expression by natural killer (NK) cells in early pregnancy.

DESIGN

Case-control study of immunologic markers.

SETTING

University hospital.

PATIENT(S)

Thirty pregnant women and 22 nonpregnant women.

INTERVENTION(S)

Peripheral venous blood sampling and decidual tissue collection after elective abortion.

MAIN OUTCOME MEASURE(S)

Flow cytometry was used to assess expression of KIR by NK cells in the cell samples.

RESULT(S)

In contrast to CD56(bright) peripheral blood NK cells, CD56(dim) cells express killer cell Ig-like receptor KIR/NKAT2. However, KIR/NKAT2 and lectin-like CD94 are present on both subsets of decidual NK cells. We found no differences between peripheral blood NK cell subsets from pregnant and nonpregnant women.

CONCLUSION(S)

Our findings demonstrate that NK cell subsets, distributed in accordance with CD56 molecule density on cell surface, express killer inhibitory receptors CD94 and KIR/NKAT2 in a different way. Our data support the view that CD56(bright)KIR/NKAT2+CD94+ decidual NK cells are specialized NK cells that have an important role to play in early pregnancy.

Expression of killer cell inhibitor receptors on immunocompetent cells with relation to graft-versus-host disease after hematopoietic stem cell transplantation

The study was aimed at the exploration of relationship between T cells expressing killer cell inhibitor receptors (KIR, CD158 and CD94) and graft-versus-host disease (GVHD) after hematopoietic stem cell transplantation. The expression rates of CD158a, CD158b and CD94 on T cells and NK cell were detected by flow cytometry and donor/recipient HLA-Cw was analyzed using PCR after peripheral blood stem cell transplantation (PBSCT) and umbilical cord blood transplantation (UCBT). After both PBSCT and UCBT, the rates of CD3(+)CD158a(+) and CD3(+)CD158b(+) T cells increased, especially the rate of CD8(+)CD158b(+) T cells. In both acute and chronic GVHD groups, the rate of CD3(+)CD158b(+) T cells increased, especially in acute GVHD. The CD94 mainly expressed on CD3(+)CD8(+) T cells. The percentage of the expression of CD94 on CD4(+) and CD8(+) cells after UCBT and PBSCT increased significantly. The expression of KIR in GVHD (early stage of transplantation) increased but the expression of KIR in chronic GVHD (advanced stage of transplantation) decreased. Five patients who HLA-Cw matched had no severe GVHD. In four patients who underwent allo-PBSCT and UCBT from related HLA-matched donors, only 2 patients had no aGVHD. Four patients underwent transplantation from unrelated HLA-matched donors had GVHD. These observations suggested that there is some relationship between GVHD and KIR expression on T cells. CD158b might be an inhibitory molecule of T cell activated at early stage after transplantation. Understanding the mechanism of GVHD with the expression of KIR on T cells, especially those binding the HLA-Cw might shed light on the establishment of the specific immunotolerance for the prevention of GVHD. To pay attention to HLA-Cw typing is very important to reduce GVHD and increase GVL effect in related or unrelated HLA-matched transplantation.

Functional and molecular characterization of a KIR3DL2/p140 expressing tumor-specific cytotoxic T lymphocyte clone infiltrating a human lung carcinoma

T lymphocytes infiltrating a human lung carcinoma stimulated in vitro with autologous tumor cell line showed a TCRVbeta13.6(+) T-cell expansion. This subset was isolated using TCRVbeta-specific antibody and several T-cell clones were generated. All these clones expressed a unique Vbeta13.6-Jbeta2.7 TCR with the same junctional region strongly suggesting that they derived from the same cell. They were CD8(+)/CD28(-) and expressed the MHC class I binding killer cell Ig-like receptor (KIR)3DL2/p140, but not KIR3DL1/p70, KIR2DL1/p58.1 and KIR2DL2/3/p58.2. Sequence analysis indicated that KIR3DL2/p140 cDNA was identical to the previously reported 3DL2*002 allele except for two nucleic acid substitutions. Functional studies showed that KIR3DL2/p140(+) CTL secrete a significant level of IFNgamma and mediate an HLA-A2-restricted cytotoxicity against the autologous and some allogeneic tumor cells but not towards the autologous EBV-B cells. Strikingly, both the lytic and the cytokine secretion activities induced upon specific cell interactions were unaffected by anti-KIR3DL2/p140 antibody. In addition, crosslinking KIR3DL2/p140 molecules on CTL did not result into the modification of cytotoxicity and cytokine production triggered by anti-CD3 antibody. These results strongly suggest that, as opposed to distinct KIR expressed by CTL, the in vitro KIR3DL2/p140 engagement does not result into inhibitory (nor activatory) effects on tumor-specific CTL.

[Killer Ig-like receptor gene content diversity and haplotype analysis in Chinese Han population in Shanghai]

OBJECTIVE

To detect the diversity of killer Ig-like receptor(KIR) gene content and the combination of haplotypes in Chinese Han population in Shanghai area.

METHODS

DNA samples from 87 randomly unrelated healthy individuals in Shanghai Han population were genotyped with SSP/PCR method.

RESULTS

(1) Frequencies of KIR genes: All of 18 known KIRs genes, such as 2DL1-5, 2DS1-5, 3DL1-3, 3DS1, KIR1D and the pseudogenes X, Xv and Z(KIR2DP1) were observed in Shanghai Hans. All individuals contain 3DL3, 2DL4, 3DL2 and 3DL1; the most common genes were 2DL3, Z, 2DL1 and X; the following were 2DS4, 1D, 2DL5, 2DS1, 3DS1 and 2DS5; the next were 2DS2, 2DL2, 2DS3 and Xv. (2) Frequencies of KIR gene haplotypes; there were 13 haplotypes detected in 87 Han individuals, among them, the most frequent one was type 2 (haplotypeA-2DS4). (3) Frequencies of KIR genotypes: 18 kinds of the combinations of the haplotypes were observed; the most frequent ones were AJ(2,2), AF (1,2). Also, In this study were identified five new genotypes FZ1 2 9 , FZ2 1 16 , FZ3 6 17 , FZ4 4 13 and FZ5 2 6 ,which had not been observed in Caucasians so far.

CONCLUSION

These findings suggest that there are distinctive frequencies of KIR gene content, haplotype as well as genotype in Chinese Han population in Shanghai area.

Expansion of natural killer cells in patients with head and neck cancer: detection of "noninhibitory" (activating) killer Ig-like receptors on circulating natural killer cells

BACKGROUND

In a group of patients with head and neck cancers (H&NC), the expansion of the population of CD3-,CD16+ natural killer (NK) cells in the peripheral blood was studied.

METHODS

Cytofluorimetric analysis of the expression of killer Ig-like receptors (KIR, namely p58.1, p58.2, p58.3, p70, and p140) and CD94-NKG2a was performed. Cytolytic activities were studied using 51Cr release assay. T and NK cell cloning was performed using limiting dilution culture conditions. Cytokine production was analyzed using commercial enzyme immunoassays.

RESULTS

Phenotypic analysis showed that the expanded populations were heterogeneous. Even in the presence of a large number of circulating NK cells, "nonspecific" cytolytic capacities were heavily reduced, whereas cytolytic capacity related to T cells was virtually normal. Unlike NK cell clones derived from healthy donors, most NK cells derived from H&NC patients expressed surface "activating" NK cell receptors (KAR) for HLA, detected by use of a redirected cytolytic assay. Analysis of the CD4+ subpopulation at the clonal level demonstrated that they had a severe proliferative defect.

CONCLUSION

These experimental data indicated that H&NC patients have a polyclonal expansion of functionally deficient NK cells expressing KAR. In addition, the proliferative capacity of patients' "helper" cells was strongly inhibited, thus accounting for a severe impairment of cytolytic activity of the expanded NK cells.