Expression of the human mucosal lymphocyte antigen, HML-1, by T cells activated with mitogen or specific antigen in vitro

Dissecting Common and Unique Effects of Anti-α4β7 and Anti-Tumor Necrosis Factor Treatment in Ulcerative Colitis

BACKGROUND AND AIMS

Vedolizumab is an anti-α4β7 antibody approved for the treatment of ulcerative colitis [UC]. Although it is assumed that vedolizumab blocks intestinal homing of lymphocytes, its effects on different intestinal cell populations are not fully stablished. In order to establish the unique mechanisms of action of vedolizumab in UC patients, we compared its effects to those induced by anti-tumour necrosis factor [TNF].

METHODS

Patients with active UC [endoscopic Mayo score >1] starting vedolizumab [n = 33] or anti-TNF [n = 45] and controls [n = 22] were included. Colon biopsies [at weeks 0, 14 and 46] and blood samples [at weeks 0, 2, 6, 14, 30 and 46] were used for cell phenotyping, transcriptional analysis [qPCR], and to measure receptor occupancy.

RESULTS

Vedolizumab, in contrast to anti-TNF, significantly reduced the proportion of α4β7+ cells within intestinal T subsets while preserving the percentage of α4β7+ plasma cells. The marked decrease in α4β7 did not change the percentage of colonic αEβ7+ cells [at 46 weeks]. Both vedolizumab and anti-TNF significantly downregulated inflammation-related genes in the colon of responders [Mayo score < 2]. Moreover, both treatments significantly decreased the percentage of intestinal, but not blood, total lymphocytes [T and plasma cells], as well as the proportion of α4β1+ cells within intestinal T lymphocytes.

CONCLUSIONS

Our data show that while vedolizumab and anti-TNF block two unrelated targets, they induce remarkably similar effects. On the other hand, vedolizumab's unique mechanism of action relies on blocking intestinal trafficking of α4β7 T cells, despite effectively binding to B and plasma cells that express α4β7.

Integrin αEβ7: molecular features and functional significance in the immune system

Alpha E beta 7 (αEβ7) is an α-I domain-containing integrin that is highly expressed by a variety of leukocyte populations at mucosal sites including intraepithelial T cells, dendritic cells, mast cells, and T regulatory cells (Treg). Expression depends largely or solely on transforming growth factor beta (TGF-β) isoforms. The best characterized ligand for αEβ7 is E-cadherin on epithelial cells, though there is evidence of a second ligand in the human system. An exposed acidic residue on the distal aspect of E-cadherin domain 1 interacts with the MIDAS site in the αE α-I domain. By binding to E-cadherin, αEβ7 contributes to mucosal specific retention of leukocytes within epithelia. Studies on αE knockout mice have identified an additional important function for this integrin in allograft rejection and have also indicated that it may have a role in immunoregulation. Recent studies point to a multifaceted role for αEβ7 in regulating both innate and acquired immune responses to foreign antigen.

Pathophysiology and role of the gastrointestinal system in spondyloarthritides

Inflammatory bowel disease (IBD) is a well-known extra-articular manifestation in spondyloarthritis (SpA); about 6.5% of patients with ankylosing spondylitis develop IBD during the course of the disease. The pathogenesis of both SpA and IBD is considered to be the result of a complex interplay between the host (genetic predisposition), the immune system and environmental factors, notably microorganisms, leading to a disturbed immune system and chronic inflammation. Over the past decade, the role of tumor necrosis factor inhibition (infliximab, etanercept, adalimumab, golimumab) in improving signs and symptoms and overall quality of life has been well documented in various forms of SpA. Future research will clarify the role of other potential targets.

The potential impact of CD4+ T cell activation and enhanced Th1/Th2 cytokine ratio on HIV-1 secretion in the lungs of individuals with advanced AIDS and active pulmonary infection

Bronchoalveolar lavage fluid (BALF) provides a source of mucosal CD4(+) T cells. We investigated the physiological properties of T lymphocytes from BALF and blood and their role on the dynamic of HIV-1 replication among AIDS patients with active lung infections. Pulmonary CD4(+) T cells consist mainly of effector memory cells (CD45RO(+) and CCR7(-)) with increased expression of activation markers (HLA-DR(+) and CD69(+)) when compared to the blood counterpart. We observed a high frequency of BALF cells capable of secreting HIV-1-Ags suggesting that the local lung environment may support favorable conditions for CD4(+) T lymphocytes harboring HIV-1 DNA to initiate the viral cycle. Nevertheless, the high number of IFN-γ-producing cells and the predominance of Th1 immune response in the lung could limit the secretion of HIV-1 RNA. In conclusion, the capacity of activated CD4(+) T cells to produce HIV-1 is driven by both the level and quality of cellular activation in the lung.

Interactions between gut inflammation and arthritis/spondylitis

PURPOSE OF REVIEW

The spectrum of spondyloarthritis is characterized by the intriguing co-occurrence of gut and joint inflammation, although no obvious anatomical link exists.

RECENT FINDINGS

Data from animal models identify stromal cells as important players in pathogenesis, although signalling through TNFRI appeared to be sufficient for development of combined gut and joint inflammation. Interleukin-23 receptor was identified as a susceptibility locus for ankylosing spondylitis.

SUMMARY

Human genome studies combined with animal model research provide us with new evidence in the fascinating field of the gut-joint axis. However, how these newly identified genetic associations can influence the immunological environment remains to be elucidated.

Joint expedition: linking gut inflammation to arthritis

The tight connection between intestinal inflammation and arthritis in spondyloarthritis (SpA) has been studied extensively. Subclinical gut inflammation, which can be considered as a model for early Crohn's disease, was shown to be strongly associated with joint inflammation. Several early mucosal abnormalities were uncovered even in the absence of histological signs of inflammation, providing clues into the pathogenesis of SpA. Nevertheless, many questions remain unanswered. In this review, we highlight recent progress on this intimate relationship between gut and joint inflammation. Emerging evidence exists favoring a role for genes beyond human leukocyte antigen B27 in the genetic predisposition of SpA and intestinal inflammation. Furthermore, the role of these predisposing genes in modulating host-pathogen interaction at mucosal surfaces and the subsequent link between gut and joint inflammation are of utmost importance in understanding the pathogenesis of SpA.

Role of the mucosal integrin alpha(E)(CD103)beta(7) in tissue-restricted cytotoxicity

The effectiveness of lung transplantation is marred by the relatively high incidence of rejection. The lung normally contains a large population of lymphocytes in contact with the airway epithelium, a proportion of which expresses the mucosal integrin, alpha(E)(CD103)beta(7). This integrin is not a homing receptor, but is thought to retain lymphocytes at the epithelial surface. Following transplantation, a population of 'tissue-restricted' cytotoxic T cells (CTL) have been identified which have the ability to lyse epithelial cells, but not major histocompatibility complex (MHC)-identical splenic cells. We tested the hypothesis that expression of the mucosal integrin confers the ability of CTL to target and destroy e-cadherin expressing targets. Immunohistochemical and flow cytometric analyses were used to demonstrate the relevance of this model to human lung. Allo-activated CTL were generated in mixed leucocyte reactions and CD103 expression up-regulated by the addition of transforming growth factor (TGF)-beta. The functional effect of CD103 expression was investigated in (51)Cr-release assays using e-cadherin-expressing transfectant targets. Human lung epithelial cells express e-cadherin and one-third of intraepithelial lymphocytes (IEL) expressed CD103. Allo-activated and bronchoalveolar lavage (BAL) lymphocytes express more CD103 than those in blood. Transfection of e-cadherin into murine fibroblasts conferred susceptibility to lysis by alpha(E)beta(7)-expressing CTL which could be blocked by specific monoclonal antibodies to CD103 and e-cadherin. CD103 functions to conjugate CTL effectors to e-cadherin-expressing targets and thereby facilitates cellular cytotoxicity. E-cadherin is expressed prominently by epithelial cells in the lung, enabling CTL to target them for destruction.

Replication of M-tropic HIV-1 in Activated Human Intestinal Lamina Propria Lymphocytes Is the Main Reason for Increased Virus Load in the Intestinal Mucosa

The gastrointestinal tract is the site of early abundant HIV replication and associated marked CD4 T-cell depletion. The aim of this study was to characterize the basis for the increased HIV replication in this compartment. Isolated mononuclear cells of the peripheral blood (PBMCs), the intestinal lamina propria (LPMCs), and purified gut lamina propria CD4 T-cell subpopulations (LP T cells) were isolated, phenotypically characterized, and infected in vitro with 2 different HIV-1 strains. T-cell subpopulations were analyzed by fluorescence-activated cell sorter. HIV-1 core protein p24 was determined in supernatants after in vitro infection. Furthermore the effect of T-cell stimulation on the replication of M- and T-tropic HIV strains was studied. In vitro replication of HIV-1 was significantly increased in CD69 compared with CD69 CD4 LP T cells, while there was no difference between CD103 and CD103 CD4 LP T cells. Experimental stimulation of LPMCs, which mimics activation by intestinal pathogens frequently present in the bowel of HIV-infected patients, further dramatically enhances HIV replication (24.5-fold) compared with nonstimulated LPMCs. M-tropic HIV-1 showed a preferential replication in LPMCs, while T-tropic HIV-1 strain showed a preferential replication in PBMCs. Thus, the elevated activation state of target cells in the intestine and not the expression of the homing marker CD103 is directly linked to massive HIV production.

Role of integrin CD103 in promoting destruction of renal allografts by CD8 T cells

Infiltration of CD8(+)TCRalphabeta(+) T-effector populations (CD8 effectors) into graft epithelial compartments has long been recognized as a key lesion in progression of clinical renal allograft rejection. While the afferent phase of allograft immunity is increasingly well-defined, the efferent pathways by which donor-reactive CD8-effector populations access and ultimately destroy the graft renal tubules (rejection per se) have received remarkably little attention. This is an important gap in our knowledge of transplantation immunology, because epithelial compartments comprise the functional elements of most commonly transplanted organs including not only kidney, but also liver, lung, pancreas, and intestine. Furthermore, there is increasing evidence that attack of graft epithelial elements by CD8-effector populations not only causes short-term graft dysfunction but is also a major contributor to development of chronic allograft nephropathy and late graft loss, which now represent the salient clinical problems. Recent studies of the T-cell integrin, alpha(E)beta(7) (CD103), have provided insight into the mechanisms that promote interaction of CD8 effectors with graft epithelial compartments. The purpose of this communication is to review the known properties of the CD103 molecule and its postulated role in the efferent phase of renal allograft rejection.

Ocular surface epithelium induces expression of human mucosal lymphocyte antigen (HML-1) on peripheral blood lymphocytes

BACKGROUND/AIMS

Peripheral blood CD8+ lymphocytes that home to mucosal surfaces express the human mucosal lymphocyte antigen (HML-1). At mucosal surfaces, including the ocular surface, only intraepithelial CD8+ lymphocytes express HML-1. These lymphocytes are retained in the intraepithelial compartment by virtue of the interaction between HML-1 and its natural ligand, E-cadherin, which is expressed on epithelial cells. The purpose of this study was to determine whether ocular surface epithelial cells (ocular mucosa) could induce the expression of human mucosal lymphocyte antigen on peripheral blood lymphocytes.

METHODS

Human corneal and conjunctival epithelial cells were co-cultured with peripheral blood lymphocytes. Both non-activated and activated lymphocytes were used in the experiments. After 7 days of incubation, lymphocytes were recovered and analysed for the antigens CD8/HML-1, CD4/HML-1, CD3/CD8, CD3/CD4, CD3/CD25, CD8/CD25, and CD4/CD25 by flowcytometry.

RESULTS

Significant statistical differences were observed in the CD8/HML-1 expression when conjunctival epithelial cells were co-cultured with non-activated and activated lymphocytes (p = 0.04 for each) and when corneal epithelial cells were co-cultured with non-activated lymphocytes (p = 0.03). Significant statistical difference in CD4/HML-1 expression was observed only when conjunctival epithelial cells were co-cultured with activated lymphocytes (p = 0.02).

CONCLUSION

Ocular surface epithelial cells can induce the expression of human mucosal lymphocyte antigen on CD8+ (and to some extent on CD4+) lymphocytes. This may allow the retention of CD8+ and CD4+ lymphocytes within the epithelial compartment of the conjunctiva and play a part in mucosal homing of lymphocytes.

Gluten-free diet has a beneficial effect on chromosome instability in lymphocytes of children with coeliac disease

OBJECTIVES

Children with coeliac disease (CD) have an increased number of chromosome aberrations in peripheral blood lymphocytes. Whether genetically determined or a secondary phenomenon in CD, chromosome abnormalities may be involved in the predisposition to cancer in CD patients. The aim of the study was to follow a group of children with CD in whom the initial frequency of chromosome aberrations at diagnosis was known and to measure the same variable after a minimum of 2 years on a gluten-free diet.

METHODS

Chromosome aberrations in peripheral blood lymphocytes were determined in 17 patients with CD, before and after at least 24 months of a gluten free diet (mean, 33 months), and in 15 healthy children. The differences in the frequency of aberrations were analyzed by Mann-Whitney U test and Wilcoxon matched-pairs signed-ranks test.

RESULTS

Twelve patients adhered to the diet and had a significantly lower frequency of chromosome aberrations than did 5 patients not following the diet (0.16% v 1.2%; P = 0.03), whereas at presentation there had been no difference (1.54% v 1.2%; P = 0.09). The frequency of aberrations at follow-up in patients who were diet adherent was significantly lower than at presentation (1.54% v 0.16%; P = 0.02) and remained unchanged in patients who were not diet adherent (1.2% v 1.2%; P = 1). After at least 24 months of a gluten-free diet, children with CD did not differ from healthy control subjects (0.16% v 0.27%; P = 0.54), whereas children not following the diet had an increased frequency of aberrations (1.2% v 0.27%; P = 0.05).

CONCLUSIONS

The frequency of chromosome aberrations in peripheral blood lymphocytes of patients with CD decreased significantly on a gluten-free diet. We conclude that genomic instability is a secondary phenomenon, possibly caused by chronic intestinal inflammation.

Expansion of CD8+ T cells with regulatory function after interaction with intestinal epithelial cells

BACKGROUND & AIMS

Regulatory T cells play a role in the control of immune responses in the intestinal mucosa and their absence may predispose to inflammatory bowel disease (IBD). We have previously shown that T cells activated by intestinal epithelial cells (IECs) are suppressive in function. Our goal was to characterize the phenotype and function of T cells proliferating after interaction with IECs.

METHODS

Irradiated human IECs, isolated from normal resection specimens, were cultured with carboxy fluorescein succinimidyl ester (CFSE) labeled T cells. Flow cytometric analysis of T cells was performed at days 5-10. CD8+ T cells proliferating in culture with IECs were sorted and added to suppressive assays.

RESULTS

The precursor frequency of T cells proliferating in response to IECs ranged from 0.3%-0.9%. Several subpopulations were shown to proliferate (CD8+CD28-/CD8+CD28+/CD4+CD25+), but one population (CD8+CD28-CD101+CD103+) appeared to be dependent on contact with the CD8 ligand gp180. After sorting, culture in the presence of interleukin (IL)-7 and IL-15 allowed for the generation of cell lines. IEC-activated CD8+ T cells, but not nonactivated CD8+ T cells, were suppressive in function. Suppression belonged to the CD101+CD103+ subset of IEC-activated CD8+ T cells and appeared to require cell contact. CD8+ lamina propria T cells also showed suppressive function, suggesting the presence of CD8+ regulatory T cells in the mucosa.

CONCLUSIONS

IECs are able to induce the proliferation of a small fraction of CD8+ peripheral T cells. The CD8+CD28- subset of IEC-activated CD8+ T cells, which express CD101 and CD103, interacts with IECs through gp180 and has regulatory function.

Role of integrin alphaE(CD103)beta7 for tissue-specific epidermal localization of CD8+ T lymphocytes

Tissue-specific T cell localization is crucial for immune surveillance of normal tissues and the pathogenesis of inflammatory disorders. In psoriatic skin, CD8+ lymphocytes predominantly reside within the epidermis, whereas CD4+ T cells are most abundant within the dermis. Molecular mechanisms guiding this spatial compartmentalization are not completely understood, however. Here, we demonstrate that 55% (+/-9.7%, n = 14) of the epidermal T cells, predominantly of the CD8+ phenotype, expressed the integrin alphaE(CD103)beta7. In contrast, only 5% (+/-2.0%) of the dermal T cells were alphaE(CD103)beta7+. Integrin alphaE(CD103)beta7 was not detected in normal skin (n = 10), and less than 1% of peripheral blood lymphocytes derived from normal (n = 11) or psoriatic (n = 10) donors expressed alphaE(CD103). When cultured T lymphoblasts (n = 12 donors) were stimulated with transforming growth factor beta1, expression of integrin alphaE(CD103)beta7 was induced on 52.8% (+/-16.2%) of CD8+ cells, but only on 6.1% (+/-2.3%) of CD4+ cells, suggesting selective inducibility on CD8+ lymphocytes. Whereas similar overall expression of transforming-growth-factor-beta1-specific mRNA was detected in normal and psoriatic skin by real-time quantitative polymerase chain reaction, immunohistochemistry revealed focal overexpression of transforming growth factor beta1 underneath psoriatic, but not normal, epidermis. This heterogenous transforming growth factor beta1 expression may contribute to induction of alphaE(CD103) in vivo. Adhesion of transforming-growth-factor-beta1-stimulated CD8+, but not CD4+, T cells to cultured keratinocytes and psoriatic epidermis in frozen sections could be significantly inhibited by antibodies that blocked the alphaE(CD103)/E-cadherin interaction. Co-culture of lymphoblasts and keratinocytes resulted in marginal enhancement of alphaE(CD103)beta7 expression in some cases. Overall, integrin alphaE(CD103)beta7 appears to contribute to tissue-specific epidermal localization of CD8+ T lymphocytes.

Studies on transcriptional regulation of the mucosal T-cell integrin alphaEbeta7 (CD103)

Integrin alphaEbeta7 is expressed almost exclusively by mucosal T cells and mucosal dendritic antigen-presenting cells (APCs) and is thought to be induced locally by transforming growth factor-beta (TGF-beta). In mice, mRNA for the alphaE subunit was found to be abundant in mucosal T cells but absent from other tissues. Exposure of a T-cell line to TGF-beta strongly up-regulated alphaE mRNA levels within 30 min, and nuclear run-on experiments established that regulation occurred at the level of transcription. The organization of the human alphaE gene and a very closely linked novel gene, ELG, was determined. The alphaE promoter was tested in T cells and fibroblasts and functioned equally well in both cell types and did not confer TGF-beta responsiveness. Regions of the promoter providing enhancer activity and phorbol 12-myristate 13-acetate (PMA) responsiveness were identified by deletion studies. DNAse 1 hypersensitivity analysis of 36 kb of the alphaE gene revealed one hypersensitive site, found only in alphaE+ cells, located near the transcription start points. These results show that, unlike the situation with other integrins, lineage specificity and cytokine responsiveness of alphaE transcription are not conferred by the proximal promoter. Specificity may depend on distant control elements that have not yet been identified.

Regulation of the epithelial cell-specific integrin, CD103, by human CD8+ cytolytic T lymphocytes

BACKGROUND

The destruction of the graft epithelium by CD8+ cytolytic T lymphocytes (CTL) is an important aspect of organ allograft rejection. Our recent finding in a mouse model that the epithelial cell-specific integrin, CD103, defines a subset of CD8+ CTL potentially sheds new light onto such interactions. The goal of the present study was to assess the relevance of these data to the human system.

METHODS

CD103 expression by human T-cell populations generated in mixed lymphocyte cultures or isolated from transplant nephrectomy specimens was quantitated using multiparameter FACS analyses.

RESULTS

CD103 defined a major subset (26-76%) of CD8+ CTL generated in human mixed lymphocyte cultures; cell sorting experiments confirmed that the CD103+ and CD103- subsets both possess allospecific lytic activity. Anti-transforming growth factor (TGF)-beta blocked the appearance of the CD103+ CTL subset, and persistent expression of CD103 by CD8+ CTL was dependent on bioactive TGF-beta. Isolated CD103+ and CD103- CD8 subsets maintained their phenotypic integrity during in vitro expansion, although optimal CD103 expression on the former was TGF-beta dependent. Although CD103+ cells were rare among activated CD8 cells in peripheral lymphoid compartments (< 10%), analyses of transplant nephrectomy specimens revealed that a major subset (21-61%) of CD8 memory/effector cells that infiltrate rejecting renal allografts express high levels of CD103.

CONCLUSIONS

We conclude that CD103 defines a discrete and stable subset of human CD8+ CTL and that CD103 expression by such cells is initiated and maintained by bioactive TGF-beta. These data point to the existence of a human effector subset that is uniquely specialized for the destruction of the graft epithelium.

Up-regulation of alphaEbeta7, a novel integrin adhesion molecule, on T cells from systemic lupus erythematosus patients with specific epithelial involvement

OBJECTIVE

To determine the possible role of a novel integrin, alphaEbeta7, in the pathogenesis of systemic lupus erythematosus (SLE).

METHODS

Expression of alphaEbeta7 was examined on peripheral blood lymphocytes (PBL) from normal subjects (n = 25) and patients with SLE (n = 31), primary Sjogren's syndrome (n = 7), or polymyositis/dermatomyositis (n = 8) by cytofluorometry and/or immunoprecipitation. Adhesion of alphaEbeta7+ T cells to HSG epithelial cells was investigated using a confocal image analyzer.

RESULTS

After phytohemagglutinin stimulation, expression of alphaEbeta7 on PBL, especially on CD8+ T cells, was significantly higher in SLE patients than in normal subjects (P<0.01). Elevated alphaEbeta7 expression was associated with the presence of oral ulcers or serositis (P<0.05). Activated SLE T cells with enhanced alphaEbeta7 expression strongly adhered to HSG; this adhesion was partially blocked by anti-alphaEbeta7.

CONCLUSION

Expression and adhesion of alphaEbeta7 on activated PBL was significantly increased in patients with SLE with epithelial involvement. This suggests a role of this novel integrin in tissue-specific retention of activated PBL, due to increased alphaEbeta7-E-cadherin interaction, which may contribute to epithelial inflammation.

Interactions between peripheral blood CD8 T lymphocytes and intestinal epithelial cells (iEC)

Intestinal intraepithelial lymphocytes (iIEL) are primarily CD8 cells and most of them have a CD28- phenotype, the phenotype of effector cytotoxic T cells. We asked whether the predominance of CD8+CD28- T cells in the gut may result from peripheral blood T cells preferentially migrating to the iIEL compartment and adhering to iEC. Compared with CD4 cells, adhesion of resting CD8+ T cells to iEC cell lines was significantly higher. Adhesion could be blocked with a MoAb to gp180, a molecule expressed on iEC which is known to interact with CD8/lck. No significant difference in the level of adhesion was observed between CD8+CD28+ and CD8+CD28- T cells. Thus CD8 cells may preferentially migrate to the iIEL compartment, but loss of CD28 expression could occur in situ after migration. Consistent with this hypothesis, the CD8+CD28- cells became enriched after co-culturing T cells with iEC cell lines and primary iEC. Induction of the CD8+CD28- phenotype in cord blood and adult T cells was observed in co-cultures with iEC and also with mitogens and superantigens. In the latter case, CD28 down-modulation was seen specifically in the Vbeta subset targeted by the superantigen, indicating that loss of CD28 expression is a direct result of T cell receptor (TCR)-mediated stimulation. The combined results suggest that CD8+CD28- T cells are antigen experienced T cells, and that they may have a survival advantage in the presence of gut epithelial cells in vitro. This may contribute to the predominance of CD8+CD28- T cells in the iIEL compartment.

HIV-1 induces cytotoxic T lymphocytes in the cervix of infected women

Although T lymphocytes are present in the genital mucosa, their function in sexually transmitted diseases is unproven. To determine if cervical T cells mediate HIV-specific cytolysis, mononuclear cells in cytobrush specimens from HIV-1-infected women were stimulated in vitro with antigen. Resultant cell lines lysed autologous targets expressing HIV-1 proteins in 12/19 (63%) subjects, and these responses were detected intermittently on repeated visits. All 8 subjects with blood CD4+ counts > or =500 cells/microl had HIV-1-specific cervical CTL, whereas only 4/11 with counts <500 cells/microl had detectable responses (P = 0.008). Class II MHC-restricted CD4+ CTL clones lysed targets expressing Env gp41 or infected with HIV-1. Class I MHC-restricted CD8+ clones recognized HIV-1 Gag- or Pol-expressing targets, and the epitopes were mapped to within 9-20 amino acids. Comparisons of intra-individual cervical and blood CTL specificities indicate that epitopes recognized by CTL in the cervix were commonly recognized in the blood. These studies provide the first definitive evidence for an MHC-restricted effector function in human cervical lymphocytes.

Expression of functional molecules by human CD3- decidual granular leucocyte clones

Cell surface and cytoplasmic antigen expression by 35 CD3- decidual granular leucocyte (DGL) clones, derived from human endometrial tissue in the first trimester of pregnancy, has been compared with both that of fresh CD3- decidual leucocytes and that of CD3- peripheral blood natural killer (PBNK) cell clones (n = 12). The majority of DGL clones retained the antigenic phenotype of fresh cells, although CD103 (HML-1) was expressed on 50% of DGL clones but only 17% of fresh DGL. Both cytoplasmic CD3 zeta and CD3 epsilon chains were detected in > 90% of DGL clones in the absence of cell surface CD3. Cytoplasmic CD3 zeta was present in almost all fresh CD3- DGL, whereas CD3 epsilon was not. Most DGL clones did not express surface Fc gamma receptors I-III (CD64, -32 and -16, respectively) and complement receptors (CR) types 1 and 2 (CD35 and 21, respectively), but 43% expressed CR3 (CD11b/18); in contrast, all PBNK clones were CR3+. The NK cell-associated molecules Kp43 (CD94) and the p58 molecule recognized by the HP3E4 monoclonal antibody were both present on a higher proportion of CD3- PBNK (91% and 50%, respectively) than DGL clones (31% and 14%, respectively), despite expression of CD94 by > 90% of fresh CD56+ decidual leucocytes. Five of 35 CD3- DGL clones expressed cytoplasmic CD3 zeta in the absence of expression of CD2, CD16 or the p58 molecule recognized by HP3E4. These variations between CD3- DGL and PBNK cell clones in expression of functional molecules may be related to previously reported differences in major histocompatibility complex-non-restricted cytotoxic activities between these two cell types.

Increase in the expression of alpha E beta 7, characteristic of intestinal intraepithelial lymphocytes, on T cells in the lung epithelium of patients with interstitial lung diseases and in synovial fluid of patients with rheumatic diseases

The intestinal epithelium contains a distinct group of lymphocytes (iIEL). The majority of iIEL are T cells characterized by a phenotype different from PBL. This phenotypic peculiarity has led to the hypothesis that iIEL, develop in a thymus-independent fashion, that they may develop locally in the gut epithelium itself and that they have the distinct function of providing a first line of defense in the gut. We looked at the expression of the gut-associated surface molecule alpha E beta 7 on T cells in inflamed tissues outside the gut epithelium. The already high frequency of 41.8% alpha E beta 7+ T cells in bronchoalveolar lavage from healthy lungs rises to a median of 61% in a fibrotic lung. In synovial fluid the percentage of T cells expressing alpha E beta 7 was diverse; it was not as high as in the lung but was elevated compared to PBL levels. In both tissues, the increase in alpha E beta 7 expression correlated with an increase in CD8+ cells. We discuss our data in the context of a model in which iIEL can leave the gut epithelium and become involved in inflammatory processes, possibly related to autoimmune disease.