KIR2DS1 and KIR2DL1-C245 Dominantly Repress NK Cell Degranulation Triggered by Monoclonal or Bispecific Antibodies, whereas Education by Uptuning Inhibitory Killer Ig-related Receptors Exerts No Advantage in Ab-dependent Cellular Cytotoxicity

NK cell responsiveness to target cells is tuned by interactions between inhibitory NK cell receptors and their cognate HLA class I ligands in a process termed "NK cell education." Previous studies addressing the role for NK cell education in Ab-dependent cellular cytotoxicity (ADCC) show ambiguous results and do not encompass full educational resolution. In this study, we systematically characterized human NK cell CD16-triggered degranulation toward defined human tumor cell lines in the presence of either the mAb rituximab or a recently developed CD34xCD16 bispecific killer engager. Despite positive correlation between killer Ig-related receptor (KIR)-mediated education and CD16 expression, NK cells educated by one or even two inhibitory KIRs did not perform better in terms of ADCC than uneducated NK cells in either missing-self or KIR-ligand matched settings at saturating Ab concentrations. Instead, NKG2A+ NK cells consistently showed more potent ADCC in the missing-self context despite lower levels of CD16 expression. KIR2DS1+ NK cells demonstrated dampened ADCC in both the missing-self and KIR-ligand matched settings, even in the presence of its ligand HLA C2. The lower response by KIR2DS1+ NK cells was also observed when stimulated with a bispecific killer engager. Surprisingly, repression of ADCC was also observed by NKG2A+ NK cells coexpressing the inhibitory KIR2DL1-C245 receptor that confers weak education. In conclusion, our study suggests that NK cell education by inhibitory KIRs does not augment ADCC per se, whereas expression of KIR2DS1 and KIR2DL1-C245 dominantly represses ADCC. These insights add to the fundamental understanding of NK cells and may have implications for their therapeutic use.

Killer cell immunoglobulin-like receptor along with HLA-C ligand genes are associated with type 1 diabetes in Chinese Han population

OBJECTIVE

Killer cell immunoglobulin-like receptor (KIR) genes and their putative ligands human leukocyte antigen (HLA)-C genes have been associated with type 1 diabetes (T1D). We hypothesize that KIR genes and their ligands HLA-C genes are important in T1D aetiology.

RESEARCH DESIGN AND METHODS

KIR and HLA-C ligand genotyping was performed in 259 T1D patients and 262 healthy children.

RESULTS

No significant difference was observed in the distribution of KIR genes between T1D patients and healthy controls. However, frequency of HLA-C1 gene and HLA-C2 gene (marginal association) was higher in patient group. The combinations 2DL2-/HLA-C1+; 2DL3+/HLA-C1+; 2DS2-/HLAC1+ were positively associated with T1D. The combinations 2DL1+/HLA-C2-; 2DL2-/HLA-C1-; 2DL3+/HLA-C1-; 2DS2-/HLAC1- were found to be negatively associated with T1D. Among the genes we tested, a combination of HLA-C1 and -C2 conferred the strongest association with T1D and the strength of this association was higher than that of HLA-C1 alone. The frequencies of KIR 2DL1, 2DL2 and 2DL3 and HLA-C1 were higher in T1D patients positive for GAD65 autoantibody; frequency of KIR 2DS4 is higher in T1D patients positive for IA-2 autoantibody. The association between KIR/HLA-C gene and autoantibody status was not statistically significant after applying Bonferroni correction.

CONCLUSION

In our study of a Han population (East China), we found no direct association of KIR genes with T1D. However, a combination of HLA-C1 and -C2 showed a positive association with T1D. Different combinations of HLA-C and KIR showed positive and negative association with T1D.

Intracellular cysteine residues in the tail of MHC class I proteins are crucial for extracellular recognition by leukocyte Ig-like receptor 1

The activity of NK cells is regulated by activating receptors that recognize mainly stress-induced ligands and by inhibitory receptors that recognize mostly MHC class I proteins on target cells. Comparing the cytoplasmic tail sequences of various MHC class I proteins revealed the presence of unique cysteine residues in some of the MHC class I molecules which are absent in others. To study the role of these unique cysteines, we performed site specific mutagenesis, generating MHC class I molecules lacking these cysteines, and demonstrated that their expression on the cell surface was impaired. Surprisingly, we demonstrated that these cysteines are crucial for the surface binding of the leukocyte Ig-like receptor 1 inhibitory receptor to the MHC class I proteins, but not for the binding of the KIR2DL1 inhibitory receptor. In addition, we demonstrated that the cysteine residues in the cytoplasmic tail of MHC class I proteins are crucial for their egress from the endoplasmic reticulum and for their palmitoylation, thus probably affecting their expression on the cell surface. Finally, we show that the cysteine residues are important for proper extracellular conformation. Thus, although the interaction between leukocyte Ig-like receptor 1 and MHC class I proteins is formed between two extracellular surfaces, the intracellular components of MHC class I proteins play a crucial role in this recognition.

KIR2DS1-positive NK cells mediate alloresponse against the C2 HLA-KIR ligand group in vitro

The inhibitory 2DL1 and activating 2DS1 killer Ig-like receptors (KIR) both have shared ligand specificity for codon sequences in the C2 group HLA-Cw Ags. In this study, we have investigated NK cell activation by allogeneic target cells expressing different combinations of the HLA-KIR ligand groups C1, C2, and Bw4. We demonstrate that fresh NK cells as well as IL-2-propagated NK cells from 2DS1-positive donors that are homozygous for the C1 ligand group are activated in vitro by B lymphoblastoid cell lines expressing the C2 group. This response is, in part, due to the absence of C1 group recognition mediated by the inhibitory receptor 2DL2/3. This "missing self" alloresponse to C2, however, is rarely observed in NK cells from donors lacking 2DS1. Even in presence of 2DS1, the NK alloresponse is dramatically reduced in donors that have C2 group as "self." Analysis of selected NK clones that express 2DS1 mRNA and lack mRNA for 2DL1 demonstrates that activation by the C2 ligand and mAb cross-linking of 2DS1 in these clones induces IFN-gamma. Furthermore, this C2 group-induced activation is inhibited by Abs to both HLA class I and the receptor. Collectively, these studies demonstrate that NK cells from 2DS1-positive donors are activated by target cells that express the C2 group as an alloantigen. This leads to increased IFN-gamma-positive fresh NK cells and induces NK allocytotoxicity in IL2-propagated polyclonal NK cells and NK clones. This study also provides support for the concept that incompatibility for the HLA-KIR ligand groups C1, C2, and Bw4 dominates NK alloactivation in vitro.

gammadelta-T cells expressing NK receptors predominate over NK cells and conventional T cells in the innate IFN-gamma response to Plasmodium falciparum malaria

Rapid production of interferon-gamma (IFN-gamma) in response to malaria by the innate immune system may determine resistance to infection, or inflammatory disease. However, conflicting reports exist regarding the identity of IFN-gamma-producing cells that rapidly respond to Plasmodium falciparum. To clarify this area, we undertook detailed phenotyping of IFN-gamma-producing cells across a panel of naive human donors following 24-h exposure to live schizont-infected red blood cells (iRBC). Here, we show that NK cells comprise only a small proportion of IFN-gamma-responding cells and that IFN-gamma production is unaffected by NK cell depletion. Instead, gammadelta-T cells represent the predominant source of innate IFN-gamma, with the majority of responding gammadelta-T cells expressing NK receptors. Malaria-responsive gammadelta-T cells more frequently expressed NKG2A compared to non-responding gammadelta-T cells, while non-responding gammadelta-T cells more frequently expressed CD158a/KIR2DL1. Unlike long-term gammadelta-T cell responses to iRBC, alphabeta-T cell help was not required for innate gammadelta-T cell responses. Diversity was observed among donors in total IFN-gamma output. This was positively associated with CD94 expression on IFN-gamma(+) NK-like gammadelta-T cells. Applied to longitudinal cohort studies in endemic regions, similar comparative phenotyping should allow assessment of the contribution of diverse cell populations and regulatory receptors to risk of infection and disease.

Increased activating killer immunoglobulin-like receptor genes and decreased specific HLA-C alleles in couples with recurrent spontaneous abortion

Accumulating evidence indicates natural killer (NK) cells play crucial roles in successful pregnancy. To investigate whether the killer cell immunoglobulin-like receptor (KIR) gene polymorphism and the corresponding specific HLA ligands in parent couples possessing a susceptibility to unexplained recurrent spontaneous abortion (RSA), we searched 73 pairs of childless couples with three or more abortions characterized as unexplained RSA and 68 pairs of healthy control couples. Peripheral blood was drawn to obtain genomic DNA which was used for a polymerase chain reaction using sequence-specific primers (PCR-SSP) in order to determine whether 15 selected KIR genes and two groups of HLA-C alleles were present. Our result showed that gene frequency of KIR2DS1 was higher in patients with RSA compared to that of control subjects (P =0.029). Increased numbers of activating KIR genes was observed in patients (P =0.041). Women who possessed more than two activating KIR genes were found more frequently in patients than those in control subjects (P =0.018). From a cohort of husband and wife couples, the women with a KIR2DS1 gene, and with a decreased group 2 HLA-C allele for the homologous inhibitory receptor KIR2DL1, had a tendency to fall into the RSA group (P =0.004). The results suggest that a genetic variation at the KIR locus influences the susceptibility to unexplained RSA in the Chinese Han population. Moreover, decreased ligands for inhibitory KIRs could potentially lower the threshold for NK cell activation, mediated through activating receptors, thereby contributing to pathogenesis of RSA.

KIR2DL1 allelic diversity: four new alleles characterized in a bone marrow transplant population and three families

Sequencing of PCR amplified genomic DNA including most of the coding region was used to identify killer cell immunoglobulin-like receptor 2DL1 alleles from three families and 77 bone marrow transplant patients and donors. Alleles 2DL1*00302 and *002 were frequently observed in addition to two other known alleles and four new alleles, 2DL1*00402, 2DL1*007, 2DL1*008, and 2DL1*009.

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.

Inhibitory receptor signals suppress ligation-induced recruitment of NKG2D to GM1-rich membrane domains at the human NK cell immune synapse

NKG2D is an activating receptor expressed on all human NK cells and a subset of T cells. In cytolytic conjugates between NK cells and target cells expressing its ligand MHC class I chain-related gene A, NKG2D accumulates at the immunological synapse with GM1-rich microdomains. Furthermore, NKG2D is specifically recruited to detergent-resistant membrane fractions upon ligation. However, in the presence of a strong inhibitory stimulus, NKG2D-mediated cytotoxicity can be intercepted, and recruitment of NKG2D to the immunological synapse and detergent-resistant membrane fractions is blocked. Also, downstream phosphorylation of Vav-1 triggered by NKG2D ligation is circumvented by coengaging inhibitory receptors. Thus, we propose that one way in which inhibitory signaling can control NKG2D-mediated activation is by blocking its recruitment to GM1-rich membrane domains. The accumulation of activating NK cell receptors in GM1-rich microdomains may provide the necessary platform from which stimulatory signals can proceed.

Phenotypic and functional changes of cytotoxic CD56pos natural T cells determine outcome of acute hepatitis C virus infection

Innate CD56(pos) natural killer (NK) and natural T (NT) cells comprise important hepatic antiviral effector lymphocytes whose activity is fine-tuned through surface NK receptors (NKRs). Dysregulation of NKRs in patients with long-standing hepatitis C virus (HCV) infection has been shown, but little is known regarding NKRs in acute infection. Treatment-naïve patients with acute HCV (n = 22), including 10 with spontaneous recovery, were prospectively studied. CD56(pos) NT levels were reduced early in acute HCV infection and did not fluctuate over time. In resolving HCV infection, NT cells with a more activated phenotype (lower CD158A and higher natural cytotoxicity receptor expression) at baseline predated spontaneous recovery. Moreover, NKG2A expression on CD56(+) NT cells correlated directly with circulating HCV RNA levels. Deficient interleukin-13 (IL-13) production by NT cells and reduced IL-2-activated killing (LAK) at baseline were associated with the ultimate development of persistence. These results indicate a previously unappreciated role for NT cells in acute HCV infection and identify a potential target for pharmacologic manipulation.

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.

Relevance of C1 and C2 epitopes for hemopoietic stem cell transplantation: role for sequential acquisition of HLA-C-specific inhibitory killer Ig-like receptor

Killer Ig-like receptors (KIR) and HLA class I ligands were studied in unrelated hemopoietic stem cell transplantation for chronic myeloid leukemia (n = 108). Significantly improved overall survival was observed in patients, which were homozygous for HLA-C-encoded group 1 (C1) ligands compared with those with group 2 (C2) ligands. Favorable outcome in the former patient group was an early effect that was highly significant in patients transplanted with G-CSF-mobilized peripheral blood and patients with advanced disease stages. In contrast, presence of C1 ligands in the donor was associated with significantly reduced patient survival. The differential roles of the two HLA-C ligands are explained in the context of a biased NK cell reconstitution, which is generally dominated by the presence of C1- but absence of C2-specific NK cells. The clinical observations are corroborated by in vitro experiments showing that NK cells derived from hemopoietic progenitor cells generally acquire the C1-specific inhibitory KIR2DL2/3 at earlier time points and with higher frequency than the C2-specific KIR2DL1. These findings define a novel determinant for understanding the role of NK cells in clinical hemopoietic stem cell transplantation.

Particular genetic variants of ligands for natural killer cell receptors may contribute to the HLA associated risk of primary sclerosing cholangitis

BACKGROUND/AIMS

Combinations of killer immunoglobulin-like receptors (KIRs) and HLA class I ligands that reduce natural killer (NK) cell inhibition have been shown to increase risk for autoimmune diseases. We aimed to clarify to what extent such combinations influence susceptibility to primary sclerosing cholangitis (PSC).

METHODS

Three hundred and sixty-five Scandinavian PSC patients and 368 healthy controls were genotyped for the presence or absence of genes encoding all KIRs using a PCR-SSP approach. KIR binding site variation of HLA-A, -B and -C was also determined.

RESULTS

The KIR gene frequencies were similar among patients and controls. However, the frequency of HLA-Bw4 and -C2, which are ligands for the inhibitory KIRs 3DL1 and 2DL1, respectively, was significantly reduced in PSC patients as compared with controls (38.2% vs. 54.7%, P(corrected)[P(c)]=0.0006 and 42.7% vs. 56.9%, P(c)=0.009, respectively). Two HLA risk haplotypes in PSC (carrying DRB1*0301 or DRB1*1501, respectively) were devoid of both of these alleles, and carried the 5.1 variant of the major histocompatibility complex class I chain-related A (MICA) gene previously reported to influence PSC susceptibility.

CONCLUSIONS

Particular variants of ligands for NK cell receptors encoded at three neighbouring genes in the HLA complex may contribute to PSC associations observed in this genetic region.

High-throughput killer cell immunoglobulin-like receptor genotyping by MALDI-TOF mass spectrometry with discovery of novel alleles

The killer cell immunoglobulin-like receptors (KIR) interact with major histocompatibility complex (MHC) class I ligands to regulate the functions of natural killer cells and T cells. Like human leukocyte antigens class I, human KIR are highly variable and correlated with infection, autoimmunity, pregnancy syndromes, and transplantation outcome. Limiting the scope of KIR analysis is the low resolution, sensitivity, and speed of the established methods of KIR typing. In this study, we describe a first-generation single nucleotide polymorphism (SNP)-based method for typing the 17 human KIR genes and pseudogenes that uses analysis by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. It is a high-throughput method that requires minute amounts of genomic DNA for discrimination of KIR genes with some allelic resolution. A study of 233 individuals shows that the results obtained by the SNP-based KIR/MALDI-TOF method are consistent with those obtained with the established sequence-specific oligonucleotide probe or sequence-specific polymerase chain reaction methods. The added sensitivity of the KIR/MALDI-TOF method allowed putative novel alleles of the KIR2DL1, KIR3DL1, KIR2DS5, and KIR2DL5 genes to be identified. Sequencing the KIR2DL5 variant proved it was a newly discovered allele, one that appears associated with Hispanic and Native American populations. This KIR/MALDI-TOF method of KIR typing should facilitate population and disease-association studies that improve knowledge of the immunological functions of KIR-MHC class I interactions.

Complexity in cattle KIR genes: transcription and genome analysis

Killer immunoglobulin (Ig)-like receptors (KIRs) are the major functional natural killer (NK) cell receptors in human. The presence of KIR genes has only recently been demonstrated in other (non-primate) species, and their expression, genomic arrangement, and function in these species have yet to be investigated. In this study, we describe the KIR gene family in cattle. KIR sequences were amplified from cDNA derived from four animals. Seventeen new sequences were identified in total. Some are alleles of two previously described genes, and the remainder are representative of at least four additional genes. These cDNA data, together with analysis of the cattle genome sequence, confirm that, as in humans, cattle have multiple inhibitory and activating KIR genes, with variable haplotype composition, and putative framework genes. In contrast to human, the majority of the cattle KIR genes encode three Ig-domain KIRs; most of the inhibitory genes encode only one immunoreceptor tyrosine-based inhibitory motif (ITIM), and the activating genes encode molecules with arginine rather than the more usual lysine in the transmembrane domain. A divergent gene, 2DL1, encodes a two Ig-domain KIR with an unusual D0-D2 structure, and a distinct signaling domain with two ITIMs. Similarity to pig and human two Ig-domain (D0-D2) KIRs suggest these may be more related to an ancestral gene than the other cattle KIR genes. Cattle have multiple NKG2A-related genes and at least one Ly49 gene; thus, the data presented here suggest that they have the potential to express more major histocompatibility complex-binding NK receptors than other species.

Influence of interleukin IL-2 and IL-12 + IL-18 on surface expression of immunoglobulin-like receptors KIR2DL1, KIR2DL2, and KIR3DL2 in natural killer cells

Natural killer (NK) cells express killer cell inhibitory receptors (KIRs) that recognize polymorphic class I MHC molecules. In the present study, we analyze the modulatory effect of IL-2 alone or a combination of IL-12 with IL-18 on surface expression of killer cell immunoglobulin-like receptors KIR2DL1, KIR2DL2, and KIR3DL2 in NK cells. Thus, it was found that IL-2 causes a significant increase in the proportion of cells with given studied receptors. Stimulation by a mixture of IL-12 and IL-18 caused significant increase in the fraction of cells with the KIR2DL1 and KIR2DL2, however no significant change in the percentage of cells with KIR3DL2 receptor on their surface was observed. The results of the study show the presence of KIRs on both resting and activated NK cells, this may suggest that KIRs have also an important role in the regulatory processes after activation of this subpopulation of cells.

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).

[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.

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.

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.

Natural Killer Receptors on CD8 T Cells and Natural Killer Cells from Different HLA-C Phenotypes in Melanoma Patients

PURPOSE

Because immune mechanisms involved in cutaneous melanoma have not been fully elucidated, efforts have been made to achieve prognosis markers and potential targets for immune therapies, but they have not been entirely fruitful thus far. Therefore, the goal of this study was to investigate the involvement of early changes in CD8 T cells and CD56 natural killer (NK) cells expressing NK receptors in different HLA-C dimorphism groups of melanoma patients.

EXPERIMENTAL DESIGN

CD8 T cells and CD56 NK cells were analyzed in 41 patients and 39 sex- and age-matched controls with different HLA-C genotypes by flow cytometry. HLA-C dimorphism at position 80 was tested by PCR sequence-specific primers and PCR sequence-specific oligonucleotide to examine whether it could mediate in the emergence of cells expressing killer cell immunoglobulin-like receptors.

RESULTS

Thirty-five of 41 patients had benign sentinel node, and showed an imbalance in the absolute number of CD8(+)DR(+) or CD8(+)CD161(+) peripheral blood T cells according to the CD28 coexpression compared with controls. CD8(+)CD28(-)CD158a(+) T and CD56(+)CD158a(+) NK cells were significantly increased in HLA-C(Lys80) homozygous nonmetastatic patients, whereas only CD56(+)CD158a(+) NK cells increased in heterozygous ones. An up-regulation of the CD158a KIR receptor was also seen on NK cells but not in T cells of patients at advanced disease stages.

CONCLUSIONS

This work provides, for the first time, evidence of immune activation in early stages of cutaneous melanoma, together with an increase of cells expressing CD158a in patients bearing the corresponding HLA-C ligand, which may be important to evaluate the disease progression and to use individualized immune therapeutic approaches.

Reduced KIR2DL1 recognition of MHC class I molecules presenting phosphorylated peptides

As initially described by K. Karre and colleagues in the missing self hypothesis, cells expressing self-MHC class I proteins are protected from NK cells attack. In contrast, reduction in the expression of MHC class I molecules due to viral infection or tumor transformation result in the killing of these "abnormal" cells by NK cells via NK-activating receptors. Thus, NK killing of target cells is determined by both negative signals coming from MHC class I proteins and by positive signals derived from the activating ligands. The bound peptide in MHC class I play an important role in the balanced recognition of NK cells. The peptide stabilizes the MHC complex and interacts directly with the NK inhibitory receptors, thus participating in the determination of the fate of the target cells. In this study we demonstrate that posttranslational modifications such as phosphorylation of the presented peptide altered the ability of NK cells to recognize MHC class I molecules. By using a consensus peptide (QYDDAVYKL) that binds HLA-Cw4 in which different positions in the bound peptide were modified by serine phosphorylation, we observed a reduction in KIR2DL1 binding that led to decreased protection from NK killing. Therefore, it might be possible that alteration in the phosphorylation pattern during tumor transformation or viral infection may result in less inhibition and, consequently, improved NK cell killing.

Detailed gene and allele content analysis of three homozygous KIR haplotypes

The killer immunoglobulin-like receptors are a highly polymorphic family of receptors encoded by 15 genes clustered on 19q13.4. Because of the complexity of the genetic analysis of the KIR cluster, much of the data regarding KIR sequences and alleles has been generated by cDNA typing and partial sequencing. Here we report the genomic sequencing of the KIR genes in individuals with three different haplotypes homozygous by descent. We provide a detailed analysis of their haplotypes and identify new alleles for KIR3DL3 and KIR2DL1. The primers we describe will be a valuable tool for studying the involvement of the KIR genes in various human diseases.

Microclusters of inhibitory killer immunoglobulin-like receptor signaling at natural killer cell immunological synapses

We report the supramolecular organization of killer Ig–like receptor (KIR) phosphorylation using a technique applicable to imaging phosphorylation of any green fluorescent protein–tagged receptor at an intercellular contact or immune synapse. Specifically, we use fluorescence lifetime imaging (FLIM) to report Förster resonance energy transfer (FRET) between GFP-tagged KIR2DL1 and a Cy3-tagged generic anti-phosphotyrosine monoclonal antibody. Visualization of KIR phosphorylation in natural killer (NK) cells contacting target cells expressing cognate major histocompatibility complex class I proteins revealed that inhibitory signaling is spatially restricted to the immune synapse. This explains how NK cells respond appropriately when simultaneously surveying susceptible and resistant target cells. More surprising, phosphorylated KIR was confined to microclusters within the aggregate of KIR, contrary to an expected homogeneous distribution of KIR signaling across the immune synapse. Also, yellow fluorescent protein–tagged Lck, a kinase important for KIR phosphorylation, accumulated in a multifocal distribution at inhibitory synapses. Spatial confinement of receptor phosphorylation within the immune synapse may be critical to how activating and inhibitory signals are integrated in NK cells.

Formation of a WIP-, WASp-, actin-, and myosin IIA-containing multiprotein complex in activated NK cells and its alteration by KIR inhibitory signaling

The tumor natural killer (NK) cell line YTS was used to examine the cytoskeletal rearrangements required for cytolysis. A multiprotein complex weighing approximately 1.3 mD and consisting of WASp-interacting protein (WIP), Wiskott-Aldrich syndrome protein (WASp), actin, and myosin IIA that formed during NK cell activation was identified. After induction of an inhibitory signal, the recruitment of actin and myosin IIA to a constitutive WIP-WASp complex was greatly decreased. Both actin and myosin IIA were recruited to WIP in the absence of WASp. This recruitment correlated with increased WIP phosphorylation, which was mediated by PKCtheta. Furthermore, the disruption of WIP expression by WIP RNA interference prevented the formation of this protein complex and led to almost complete inhibition of cytotoxic activity. Thus, the multiprotein complex is important for NK cell function, killer cell immunoglobulin-like receptor inhibitory signaling affects proteins involved in cytoskeletal rearrangements, and WIP plays a central role in the formation of the complex and in the regulation of NK cell activity.

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.

Killer immunoglobulin-like receptor and human leukocyte antigen expression as immunodiagnostic parameters for pelvic endometriosis

PROBLEM

We investigated host immunologic responses to endometriosis by comparing immune cell surface antigens in peripheral blood (PB) and peritoneal fluid (PF) from women with endometriosis with those in PB and PF from other patients.

METHOD OF STUDY

Japanese women with endometriosis (n = 56) were compared with controls with other laparoscopic diagnoses (n = 68). PB and PF were collected at the time of laparoscopy for flow cytometry.

RESULTS

No significant difference in phenotypic parameters of T cells (CD3, CD4, and CD8), B cells (CD19), natural killer (NK) cells (CD56), or monocytes/macrophages (CD14) was seen between women with and without endometriosis. However, increased killer immunoglobulin-like receptor (CD158a) expression by NK cells and decreased human leukocyte antigen (HLA)-ABC and -DR expression by macrophages, all suggesting decreased functional activation were found in endometriosis. These markers showed significant association with endometriosis by odds ratio, logistic regression, and decision tree analyses.

CONCLUSIONS

Increased CD158a(+) NK cells in PB and PF indicated decreased NK cell cytotoxicity in endometriosis, while decreased HLA expression on PF macrophages suggested impaired antigen presentation. Thus, aberrant immune responses by NK cells and macrophages may represent risk factors for endometriosis.

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.

Identification of a single killer immunoglobulin-like receptor (KIR) gene in the porcine leukocyte receptor complex on chromosome 6q

Human killer immunoglobulin-like receptors (KIR) are expressed on natural killer (NK) cells and are involved in their immunoreactivity. While KIR with a long cytoplasmic tail deliver an inhibitory signal when bound to their respective major histocompatibility complex class I ligands, KIR with a short cytoplasmic tail can activate NK responses. The expansion of the KIR gene family originally appeared to be a phenomenon restricted to primates (human, apes, and monkeys) in comparison to rodents, which via convergent evolution have numerous C-type lectin-like Ly49 molecules that function analogously. Further studies have shown that multiple KIR are also present in cow and horse. In this study, we have identified by comparative genomics the first and possibly only KIR gene, named KIR2DL1, in the domesticated pig (Sus scrofa) allowing further evolutionary comparisons to be made. It encodes a protein with two extracellular immunoglobulin domains (D0 + D2), and a long cytoplasmic tail containing two inhibitory motifs. We have mapped the pig KIR2DL1 gene to chromosome 6q. Flanked by LILRa, LILRb, and LILRc, members of the leukocyte immunoglobulin-like receptor (LILR) family, on the centromeric end, and FCAR, NCR1, NALP7, NALP2, and GP6 on the telomeric end, pig demonstrates conservation of synteny with the human leukocyte receptor complex (LRC). Both the porcine KIR and LILR genes have diverged sufficiently to no longer be clearly orthologous with known human LRC family members.

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.

Homozygosity for human leucocyte antigen-C ligands of KIR2DL1 is associated with increased risk of relapse after human leucocyte antigen-C-matched unrelated donor haematopoietic stem cell transplantation

Human leucocyte antigen (HLA)-C molecules regulate the function of natural killer cells and may be subdivided into two groups, C(1) and C(2), based on their specificity for inhibitory killer immunoglobulin-like receptors. We analysed the impact of the HLA-C genotype on outcome of HLA-C-matched unrelated donor haematopoietic stem cell transplantation (URD-HSCT) recipients. HLA-C(2) homozygous patients (n = 18) had lower probability of overall survival (P = 0.01) and disease-free survival (P = 0.02), resulting from increased relapse rate (P = 0.02) when compared with both HLA-C(1) homozygous (n = 43) and HLA-C(1),C(2) heterozygous (n = 50) subgroups. Patients lacking HLA-C(1) should, therefore, be considered at increased risk of relapse following HLA-C-matched URD-HSCT.

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.

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.

Recognition of peptide-MHC class I complexes by activating killer immunoglobulin-like receptors

Inhibitory receptors for MHC class I molecules increase the threshold of lymphocyte activation. Natural Killer (NK) cells express a large number of such inhibitory receptors, including the human killer Ig-like receptors (KIR). However, activating members of the KIR family have poorly defined ligands and functions. Here we describe the use of activating KIR tetramer reagents as probes to detect their ligands. Infection of cells with Epstein-Barr virus leads to expression of a detectable ligand for the activating receptor KIR2DS1. In this case, KIR2DS1 interacts with up-regulated peptide-MHC class I complexes on Epstein-Barr virus-infected cells in a transporter associated with antigen processing (TAP)-dependent manner. In tetramer-based cellular assays and direct affinity measurements, this interaction with MHC class I is facilitated by a broad spectrum of peptides. KIR2DS1 and its inhibitory homologue, KIR2DL1, share sensitivity to peptide sequence alterations at positions 7 and 8. These results fit a model in which activating and inhibitory receptors recognize the same sets of self-MHC class I molecules, differing only in their binding affinities. Importantly, KIR2DS1 is not always sufficient to trigger NK effector responses when faced with cognate ligand, consistent with fine control during NK cell activation. We discuss how our results for KIR2DS1 and parallel studies on KIR2DS2 relate to the association between activating KIR genes and susceptibility to autoimmune disorders.

Expression of inhibitory-motif killer immunoglobulin-like receptor, KIR2DL1, is increased in natural killer cells from women with pelvic endometriosis

PROBLEM

We investigated inhibitory and activation motif expression of killer immunoglobulin-like receptor (KIR) by natural killer (NK) cells, which may be pathogenetically involved in endometriosis.

METHOD OF STUDY

We compared cells from 24 Japanese women laparoscopically diagnosed with endometriosis, to cells from 25 women with other laparoscopic diagnoses. KIR expression by NK cells was assessed in peripheral blood (PB) and peritoneal fluid (PF) by flow cytometry. Intracellular immunoreceptor tyrosine-based (IT) inhibitory and activation motifs (ITIM and ITAM) of KIR in PB was assessed by Western blotting.

RESULTS

ITIM-KIR expression by PB NK cells was significantly and similarly greater than ITAM-KIR expression in women with and without endometriosis. Percentages of CD56(+) NK cells in PB and PF did not differ significantly between women with and without endometriosis; however, the percentage of CD158a(+) cells among CD56(+) NK cells in PB and PF was significantly higher in women with than without endometriosis.

CONCLUSIONS

ITIM-KIR expressing NK cells might confer tolerance to peritoneal endometriotic implants.

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.

Gene for the activating natural killer cell receptor, KIR2DS1, is associated with susceptibility to psoriasis vulgaris

Psoriasis vulgaris, particularly its juvenile form, is strongly associated with the HLA-Cw*06 allele encoding the HLA-Cw6 molecule. This molecule is recognized by the inhibitory receptor KIR2DL1 and the activatory receptor KIR2DS1, which are expressed on natural killer cells and subpopulations of T lymphocytes. Humans differ by the presence or absence of particular KIR genes. We hypothesized that either activatory KIR2DS1 or inhibitory KIR2DL1 gene frequencies might be different in psoriatic patients from a control population. Therefore, we compared the frequencies of KIR2D inhibitory (L) and activatory (S) genes in 116 psoriasis vulgaris patients and in 123 healthy controls. Fourteen novel gene combinations were found. KIR2DS1 was present in 85% of the patients, but only in 51% of the controls (corrected p [pc] < 0.0009). Similarly, HLA-Cw*06 was much more frequent in patients (77%) than in controls (17%; pc < 0.00002). Statistical analysis suggests that, although the contribution of these two factors to psoriasis is partially independent, they interact nevertheless. This result strongly speaks for a role of KIR2DS1 on recognition of HLA-Cw6 in susceptibility to psoriasis.

Haplotype analysis of killer cell immunoglobulin-like receptor genes in 77 Korean families

Killer cell immunoglobulin-like receptor (KIR) genes constitute a multigene family whose genomic diversity is achieved through variation in gene content and allelic polymorphism within individual KIR genes. To date, 16 KIR genes and pseudogenes have been identified, and group A and group B haplotypes are characterized by a dominance of genes encoding inhibitory and activating receptors, respectively. In the present study, we have investigated the presence or absence of 16 KIR genes and pseudogenes and subtypes of four genes (3DP1, 3DP1 variant; 2DL1, 2DL1 variant; expressed and nonexpressed variant of 2DL5; full length and deleted form of 2DS4) in 352 members of 77 unrelated Korean families using a PCR-based sequence-specific priming method. KIR haplotypes were determined by segregation analysis. A total of 29 different KIR genotypes and 19 (two group A and 17 group B) haplotypes were identified in 154 parents. The distribution of genotypes, in terms of combination of haplotypes, was AA 55.2%, AB 36.4%, and BB 8.4%. Different from Caucasians, full-length 2DS4 (80.5%) was the predominant subtype of 2DS4 and group A (73.4%) outnumbered group B haplotypes (26.6%). The KIR gene frequencies and the predominance of A haplotypes in Koreans are similar to those in the Japanese.

A HLA-Cw6 specific single-chain antibody fragment (scFv) recognizing a natural killer cell receptor epitope

Major histocompatibility complex (MHC) class I molecules induce inhibitory signals on natural killer (NK) cells via killer cell immunoglobulin-like receptors (KIR). We recently reported a human single-chain antibody (scFv#1), which recognizes an epitope on HLA-Cw6 (genotype: *0602). Flow cytometry showed scFv#1 binding to HLA-Cw6 (strong) and also to HLA-Cw2, 4, 5 (very weak) but not to HLA-Cw1, 3, 7, 8. The presumptive epitope of the antibody fragment, which includes residues Asn77 and Lys80 was verified by introducing point mutations into HLA-Cw6 encoding cDNAs. Asn77 --> Ser77 (N77S) and Lys80- -> Asn80 (K80N) mutants of Cw6 lost scFv#1 binding capacity whereas an additional mutation at aa position 90 (Asp-->Ala, D90A) did not influence scFv#1 binding characteristics. Since residues 77 and 80 of HLA-C are directly involved in KIR/MHC interaction, we expected the induction of target cell lysis upon addition of scFv#1 when bringing NK and HLA-Cw6 positive cells together. To prove this interference, we performed Cr-release assays, using Cw*0602 and mock-transfected K562 erythroleukemia cells as targets and freshly prepared peripheral blood NK cells as effector cells. scFv#1 appeared to influence KIR on ligand binding and restored lysis at low effector to target (E/T) ratios. Pan HLA class I antibody W6/32 did not show such effects. Taken together scFv#1 binding patterns with mutagenized HLA-Cw6 and Cr-release assays are strong evidence that the scFv#1 epitope on HLA-Cw6 is at or close to the binding site of CD158a.

[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.

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.