Phenotypical and Functional Characterization of Small Intestinal TcRγδ+ T Cells in Coeliac Disease

Increased numbers of TcR gamma delta + T cells are present in the small intestinal epithelium of patients with coeliac disease (CoD). Their function, however, is unknown. In order to facilitate detailed functional studies, intestinal gamma delta T cells have been isolated from small intestinal biopsies of patients with CoD (n = 18) and controls (n = 14). As expected, increased numbers of V delta 1+ TcR gamma delta + T cells were detected in freshly isolated intraepithelial cell suspensions (IEL) from CoD patients. Also, in the in vitro expanded IEL T-cell populations from CoD patients the numbers of V delta 1+ TcR gamma delta + T cells were increased compared with similar cell cultures from control patients. From IEL cultures derived from six CoD patients, 107 T-cell clones were generated by limiting dilution and analysed. Sixty of these clones were either CD4 or CD8 positive TcR alpha beta + clones. The remaining 47 clones expressed the TcR gamma delta. Further phenotypical analysis of the gamma delta T-cell clones indicated that the TcR gamma delta + T-cell population in the small intestinal epithelium of CoD patients is heterogeneous: four TcR gamma delta phenotypes could be detected and, although the majority of the TcR gamma delta + T cells were CD4 CD8, gamma delta T-cell clones expressing either a CD8 alpha alpha homodimer, a CD8 alpha beta heterodimer or CD4 were also identified. In contrast to the TCR alpha beta + IEL, most TcR gamma delta + IEL were CD5 negative. Furthermore, biochemical analysis indicated that the increase in V delta 1+ gamma delta T cells in the small intestinal epithelium of CoD patients was not the result of a monoclonal expansion. The small intestinal epithelium-derived gamma delta T-cell clones were functional in vitro since the majority of these clones were able to lyse target cell lines such as K562. Molt4 and Daudi. These novel findings therefore indicate that the gamma delta T cells in the small intestine of CoD patients represent a heterogeneous population and that such cells are functional in vitro. The isolation and the in vitro propagation and cloning of these cells may open new avenues for the study of the putative immune mechanisms leading to coeliac disease.     

Intraepithelial T Cells of the TcRγ/δ+CD8− and Vδ1/Jδ1+ Phenotypes are Increased in Coeliac Disease

Expression of the gamma/delta T-cell receptor (TcR) for antigen on CD3+ intraepithelial lymphocytes (IEL) was studied in situ by two-colour immunofluorescence on jejunal tissue sections from 24 patients with coeliac disease and 17 controls. The proportion of intraepithelial TcR gamma/delta+ cells was significantly increased (P less than 0.002) in untreated (median 20%, range 11-53%) as well as in treated (gluten-free diet) coeliac disease (median 23%, range 16-55%) compared with controls (median 2%, range 0-39%). Although TcR alpha/beta+ IEL dominated both in controls and coeliac disease, T cells expressing the TcR gamma/delta were preferentially located within the epithelium rather than in the lamina propria. Paired staining for TcR gamma/delta and CD8 revealed that most (approximately 90%) intraepithelial TcR gamma/delta+ lymphocytes in coeliac disease were CD8-. A remarkably large fraction (median 67%, range 58-94%) of intraepithelial TcR gamma/delta+ cells expressed the V delta 1/J delta 1-encoded epitope revealed by monoclonal antibody delta TCS1. Our results suggested that increase of the intraepithelial TcR gamma/delta+ CD8- subset of T cells is particularly related to coeliac disease.     

Gamma delta T cell receptor-positive cells of the human gastrointestinal mucosa: occurrence and V region gene expression in Heliobacter pylori-associated gastritis, coeliac disease and inflammatory bowel disease.

T cells expressing the gamma delta heterodimer of the T cell receptor (TCR) were studied with respect to their occurrence and expression of gamma delta TCR variable region (V) genes in the normal gastrointestinal mucosa and in a variety of inflammatory conditions. In controls, gamma delta TCR+ cells were a minority population confined to the epithelial compartment of stomach, small bowel and colonic mucosae. Unlike in the periphery, gastro-intestinal gamma delta TCR+ intraepithelial lymphocytes (IEL) were mainly V delta 1+ (89.98 +/- 17.70%); few were V delta 2+ (6.04 +/- 13.8%) or V gamma 9+ (11.38 +/- 10.73%). All gamma delta TCR+ IEL were CD5low; nearly half were CD8+ and the remainder were CD4-CD8- 'double negatives'. There was no significant change from normal in percentages of gamma delta TCR+ IEL in H. pylori-associated gastritis, Crohn's disease and ulcerative colitis. However, in coeliac disease, gamma delta TCR+ IEL were elevated from 2.54% (+/- 1.71) in controls to 29.6% (+/- 16.1) in untreated patients (P less than 0.001) and 18.5% (+/- 7.2) in treated patients (P less than 0.001) and more were CD4-CD8-. Otherwise, gamma delta TCR+ IEL phenotypes were little changed: the majority remained V delta 1+V delta 2-V gamma 9- and all were CD5low. These data suggest that increased gamma delta TCR+ IEL are not a generalized response to intestinal inflammation or to stress proteins, although the typical V delta 1+V delta 2-V gamma 9- CD5low phenotype is retained.     

Intraepithelial TcR alpha/beta+ lymphocytes express CD45RO more often than the TcR gamma/delta+ counterparts in coeliac disease.

Expression of CD45RO on intraepithelial lymphocytes (IEL) bearing the T-cell receptor (TcR) alpha/beta or gamma/delta was studied in situ by three-colour immunofluorescence on jejunal tissue sections from 21 patients with coeliac disease and eight controls. CD45RA-TcR alpha/beta+ IEL expressed CD45RO significantly more often (75%) than the preferentially expanded TcR gamma/delta+ counterpart (59%). Triple staining for CD3, CD4/8 and CD45RA or CD45RB revealed that all CD3 + 4 - 8 - IEL (taken to be TcR gamma/delta+) expressed CD45RB and none were CD45RA. CD45RO positivity was of the same magnitude (66%) on the predominating monoclonal antibody delta TCS1-reactive fraction of TcR gamma/delta+ cells as on the remainder of the TcR gamma/delta+ subset. These results suggest that gluten exposition in patients with coeliac disease leads to accumulation of CD45RA-, putative antigen-primed memory cells of both TcR phenotypes. The less marked CD45RO expression within the preferentially expanded TcR gamma/delta+ subset of IEL may be of particular biological interest.     

Increase in T‐Cell Subsets of Oral Mucosa: a Late Immune Response in Patients with Treated Coeliac Disease?*

BACKGROUND AND AIMS: In coeliac disease, the gut involvement is gluten-dependent. Following the introduction of a gluten-free diet, inflammatory cell infiltration decreases in the small intestinal mucosa. Our hypothesis was that the oral mucosa might mirror the changes found in coeliac disease similarly to the mucosa of the small intestine. Thus, the number of inflammatory cells in the oral mucosa would decrease in patients with coeliac disease on a gluten-free diet. METHODS: The distribution CD45RO+ and CD3(+) T cells, T-cell subpopulations (CD4(+), CD8(+), T-cell receptor (TCR)alpha beta+ and TCR gamma delta+ cells) and HLA DR expression were studied in the buccal mucosa of 15 untreated and 44 gluten-free diet treated coeliac disease patients, and of 19 controls. All 15 patients with untreated coeliac disease were immunglobulin (Ig)A endomysial antibody positive and all 44 patients on gluten-free diet except one were endomysial antibody negative, as were all control subjects. RESULTS: Untreated coeliac disease patients did not differ from controls in the densities of CD45RO+ cells, CD3(+) cells or of T-cell subsets. In contrast, in treated coeliac disease patients, a significant increase in the numbers of mast cells, CD3(+) and CD4(+) lymphocytes was found in the lamina propria of oral mucosa as compared with patients with untreated coeliac disease and controls. The increase in CD3(+) T cells was in part owing to an increase in lymphocytes expressing no TCR. No differences were found in the expression of human leucocyte antigen (HLA) DR in the epithelium or in the lamina propria in the patient groups studied or in the controls. In treated coeliac disease patients only a few TCR gamma delta+ T cells were found intraepithelially and in the lamina propria, but these cells were not detected in the lamina propria of oral mucosa of patients with untreated coeliac disease or in the controls. CONCLUSIONS: The infiltration of T cells into oral mucosa was increased in treated coeliac disease patients in spite of adherence to a gluten-free diet. Because the CD3(+) T cell count was higher than those of the TCR alpha beta+ and TCR gamma delta+ T cells, there must be other cells involved, probably natural killer (NK) cells. The increase in T-cell subsets in the treated coeliac disease patients seems not to result from poor dietary compliance, but might occur as a late immune response in coeliac disease and reflect chronic immunologic stimulation followed by regeneration of memory T cells.     

Expression of disulfide-linked and non-disulfide-linked forms of the T cell receptor gamma/delta heterodimer in human intestinal intraepithelial lymphocytes

Immunohistochemistry has been used to investigate disulfide- and non-disulfide-linked forms of the T cell receptor gamma/delta heterodimer (TcR gamma/delta) in blood and intestinal epithelium of normal human small intestine, intestine of patients with untreated coeliac disease (in whom T cells expressing TcR gamma/delta are disproportionately raised), intestine of patients with tropical malabsorption, and in the human fetus. In blood from adult volunteers, 90% of T cells expressing TcR gamma/delta use the disulfide-linked form. In contrast in the epithelium in normal small intestine, coeliac disease and tropical malabsorption, most of the T cells expressing TcR gamma/delta use the non-disulfide-linked form. This is especially prominent in untreated coeliac disease where the increase in TcR gamma/delta T cells is mainly restricted to those using the non-disulfide-linked form. In human fetal small intestinal epithelium, however, only cells using the disulfide-linked form are present. These variations in expression of different forms of TcR gamma/delta in the gut epithelium in different conditions suggests that antigen, or some as yet undefined factor may determine the frequency of each subpopulation.     

Changing jejunal gamma delta T cell receptor (TCR)-bearing intraepithelial lymphocyte density in coeliac disease.

The function of jejunal intraepithelial gamma delta+ T cells is obscure, but they are commonly implicated as playing a role in inflammatory and autoimmune conditions. In coeliac disease (CoD), there are controversial reports as to gluten dependency of these cells. We have now studied the small bowel mucosal intraepithelial T cell densities, and the ratios of gamma delta+ to CD3+ T cells and gamma delta+ to alpha beta+ T cells during early disease development and on a gluten-free diet. Nine children initially excluded for CoD were followed up and rebiopsy after 0.8-4.5 years showed mucosal deterioration. Further, 21 biopsy specimens from newly diagnosed CoD patients were studied, together with 20 specimens taken from children on a gluten-free diet. During CoD development the density of gamma delta+ and alpha beta+ T cells as well as the ratios of gamma delta+ to CD3+ T cells and gamma delta+ to alpha beta+ T cells increased. In the latent stage of CoD when the small bowel mucosal architecture was still normal, two children had clearly normal densities of gamma delta+ (< 2.5 cells/100 epithelial cells) and alpha beta+ (< 25.0 cells/100 epithelial cells) T cells, and low ratios as well. In patients with newly diagnosed CoD the densities decreased significantly on a long-term gluten-free diet. We conclude that the density of intraepithelial gamma delta+ T cells as well as alphabeta+ T cells in CoD is gluten-dependent. CoD can develop in a child ingesting normal amounts of gluten and having normal jejunal mucosal morphology on biopsy and a normal density of gamma delta+ T cells.     

T cell receptor-bearing cells among rat intestinal intraepithelial lymphocytes are mainly alpha/beta+ and are thymus dependent

Rearrangement of both the beta and gamma chain T cell receptor (TcR) genes was detected in intestinal intraepithelial lymphocytes (IEL) from normal euthymic rats. Flow cytometric analyses showed that about 73% of the IEL were CD3+ (1F4) and that 67% were TcR alpha/beta+ (R73). About 5% of the IEL were found to be CD3+, TcR alpha/beta- in double-labeling experiments suggesting that a small fraction of IEL in the rat express the alternative TcR gamma/delta. More than 70% of the IEL were granular implying that many CD3+ IEL are granular. In IEL from athymic nude rats no rearrangement of either the TcR beta or gamma chain genes or surface expression of CD3 or TcR alpha/beta was detected despite the fact that about 95% of the cells were granular and morphologically similar to those in normal rats. Taken together our data suggest that the majority of IEL in the rat express the conventional TcR alpha/beta and that TcR-bearing cells in the gut epithelium are thymus dependent.     

Phenotypical characterization of peripheral blood T cells in patients with coeliac disease: elevation of antigen-primed CD45RO+ T lymphocytes.

Increased numbers of gamma delta T-cell-receptor-bearing (TCR gamma delta +) lymphocytes are present in the small intestinal epithelium of patients with coeliac disease (CoD). In this study the phenotypic characteristics of peripheral blood T cells from 14 untreated CoD patients and 14 healthy age- and sex-matched controls were determined with special emphasis on TCR gamma delta + lymphocytes. We also studied samples taken from 15 CoD patients who were on gluten-free diet (GFD). Two- and three-colour flow cytometry analyses were performed using a whole-blood lysing method. There was no significant difference between the percentages of TCR gamma delta + lymphocytes in patients and controls. However, the amount of delta TCS1+ lymphocytes was significantly lowered in untreated patients (0.48 +/- 0.42% in CoD versus 0.86 +/- 0.57% in controls, P < 0.05). The percentage of CD45RO+ T cells, which are a primed population of T cells including memory cells, was significantly raised in the peripheral blood of untreated patients. This phenomenon was most prominent within the TCR gamma delta + population (83.9 +/- 12.2% in CoD versus 65.5 +/- 14.7% in controls, P < 0.01), but the same applies to CD45RO+ TCR alpha beta + and delta TCS1+ T cells. In patients on GFD these changes seem to be at least partly corrected. Antigen-primed CD45RO+ T cells have been shown to accumulate in the jejunal epithelium of patients with untreated CoD. The enhanced 'memory activity' also found in the peripheral blood of untreated CoD patients may result from a continuous antigenic stimulus and this stimulus could be gluten triggered.     

A major fraction of human intraepithelial lymphocytes simultaneously expresses the gamma/delta T cell receptor, the CD8 accessory molecule and preferentially uses the V delta 1 gene segment

The frequency of T cell receptor (TcR) type and the variable gene segment expression in human intraepithelial lymphocytes (IEL) from the large intestinal mucosa were studied by flow cytometry and immunohistochemistry, and compared to those in peripheral blood lymphocytes (PBL) - or lamina propria lymphocytes (LPL). Employing anti-gamma/delta TcR and anti-alpha/beta TcR monoclonal antibodies (mAb), flow cytometric analysis revealed that a large fraction of IEL (37%) are gamma/delta T cells, whereas within LPL and PBL gamma/delta T cells comprise a minor population (4.6% and 3.8% respectively). At these sites the number of gamma/delta T cells labeled with anti-CD8 mAb were 58.3% (IEL), 43.3% (LPL) and 24.4% (PBL). In situ staining of serial sections of large intestine confirmed these results. Hence, these data suggest a selective accumulation of CD8+ gamma/delta T cells in the human epithelium of the large intestine. Furthermore, analysis of gamma/delta TcR bearing IEL+ disclosed a marked preponderance of cells using the V delta 1 gene segment, whereas gamma/delta TcR+ PBL preferentially express V delta 2. Strikingly, the majority of these V delta 1+ IEL bear the CD8 molecule on their surface. These results are taken as evidence for a selective localization of V delta 1+ CD8+ gamma/delta T cells in the epithelium of the large intestine.     

Sequential development of intraepithelial gamma delta and alpha beta T lymphocytes expressing CD8 alpha beta in neonatal rat intestine: requirement for the thymus.

Previous studies in congenitally athymic nude rats have suggested that the thymus is important for the development of intestinal T cells. Here we have examined the effect of the nude mutation on intraepithelial lymphocyte (IEL) development from the perinatal period. By immunohistochemistry it was shown that CD3(-)CD8 alpha alpha + putative IEL precursors colonized the epithelium of both normal and athymic neonatal rats. Mature T cells, however, did not develop in athymic neonates. In normal rats, gamma delta T cells were present at birth and alpha beta T cells appeared within 8 days of postnatal life. At this age, the composition and relative number of intraepithelial T cells were similar to that in normal adult rats, with the exception that most neonatal T-cell receptor-gamma delta + and -alpha beta + IEL expressed CD8 beta. By contrast, extrathymic T-cell maturation in the gut of congenitally athymic rats occurred slowly, as CD3+ IEL did not appear until 4-6 months of age. These intraepithelial T cells displayed variable phenotypes and appeared to be induced by environmental antigens as they were not found in isolator-kept old nudes. In conclusion, the present results indicate that the major colonization of the gut epithelium with gamma delta and alpha beta T cells expressing CD8 alpha beta takes place perinatally and requires the presence of the thymus. The developmental relationship between these neonatal T cells and more immature CD3- CD8 alpha alpha +/- IEL remains elusive.     

Lymphocyte subpopulations in the human small intestine. The findings in normal mucosa and in the mucosa of patients with adult coeliac disease

Lymphocyte subpopulations in human small intestinal mucosa have been studied using an immunofluorescence technique on tissue sections. In the normal intestine, the majority of intraepithelial lymphocytes (IEL) were of suppressor-cytotoxic phenotype (HuTLA+ UCHTI+ OKT8+ OKT4-; 84%). Only one-third of these OKT8+IEL reacted with anti-Leu-1, and antibody directed towards a 67,000 dalton antigen found on peripheral blood T cells. IEL failed to express the activation antigen, Tac, and also lacked detectable C3b receptor (C3RTO5-). The remaining T IEL, as well as the predominant lamina propria T lymphocytes (LPL), were OKT4+ OKT8-, helper type T cells. Most of the lamina propria OKT8+ cells were also Leu-1-. In patients with adult coeliac disease, the proportions of OKT8+ and OKT4+ lymphocytes in the epithelium were not altered. However, the proportion of OKT8+ Leu-1+TIEL was significantly increased (56 vs 32%; P less than 0.02). IEL were also HLA-DR-, Tac- and C3RTO5-. The proportion of OKT8+ cells in the lamina propria was slightly, but significantly, increased (40 vs 32%; P less than 0.005). Mucosal findings in treated patients did not differ from normal. Lymphocytes with the phenotype of natural killer cells (HNK-1) were rarely found in normal or diseased mucosa. No alterations in the proportions of circulating T lymphocytes or their subsets were found in patients with coeliac disease. These findings illustrate the heterogeneity of lymphocyte subpopulations in normal and in diseased small intestinal mucosa. The changes found in adult coeliac disease may reflect the increased traffic of IEL into the epithelium.     

Expression of the LFA-1 β2 Integrin (CD11a/CD18) and ICAM-1 (CD54) in Normal and Coeliac Small Bowel Mucosa

The leucocyte adhesion molecules (beta 2 integrins) comprise CD11 alpha-chains and a common beta-chain (CD18). CD11a (leucocyte function-associated antigen 1, LFA-1) is expressed by most T cells, and is involved in antigen presentation by macrophages via its counter-receptor, intercellular adhesion molecule (ICAM-1, CD54). By criteria of double-label immunofluorescence of cryostat tissue sections, virtually all lamina propria T cells of the normal small bowel were found to express LFA-1 strongly. By contrast, only 30-60% of intra-epithelial lymphocytes (IEL) expressed detectable LFA-1, most of which were LFA-1 weak and CD18-. ICAM-1 was expressed strongly only by vascular endothelium. In coeliac disease, there was a modest increase of diffuse ICAM-1 expression in the lamina propria, mainly in the subepithelial zone, where ICAM-1+ macrophages were occasionally seen. There was also a slight overall increase in CD11a expression by IEL, seen predominantly in surface epithelium and mainly by the CD4+ minority subset, but not by CD4-CD8- (TcR gamma delta +) cells. These data suggest that the LFA-1/ICAM-1-dependent antigen presentation pathway is of minor importance to IEL in the normal small bowel, and does not assume a major role in coeliac disease.     

Presence of intestinal intraepithelial lymphocytes in mice with severe combined immunodeficiency disease.

The murine intestinal epithelium contains a heterogeneous population of intraepithelial leukocytes (IEL) most of which are granulated, Thy-1-CD5-CD8+. In order to assess the lineage relationship of this subgroup of IEL to peripheral T cells, we examined IEL in mice with the severe combined immunodeficiency (scid/scid) mutation, which lack T and B cells in peripheral lymphoid tissues. Electron and light microscopy showed that the intestine from scid/scid mice had granulated IEL similar to IEL in normal C.B-17 mice. Flow cytometry of isolated IEL stained with monoclonal antibodies against Thy-1, CD3, CD4, CD5 and CD8 showed that scid/scid mice IEL contained cells with the Thy-1-CD4-CD5-CD8+ phenotype. Immunohistochemical staining of IEL in tissue sections with antibodies to Thy-1 and CD8 confirmed that the Thy-1-CD8+ cells were in the intestinal epithelium. These scid/scid IEL also lacked CD3 expression and mRNA for the V gamma 7 V region gene of the gamma T cell receptor. We conclude that scid/scid mice contain precursors for IEL that can differentiate into a granulated Thy-1-CD5-CD8+ IEL in the intestine. The absence of CD8+ peripheral T cells in these mice suggests that these IEL differ from classical T cells in their ability to differentiate and express CD8 and do not require T cell receptor expression for their localization to the intestine.     

T Lymphocytes in Human Gut Epithelium Preferentially Express the α/β Antigen Receptor and are often CD45/UCHL1-Positive

A revived interest in intraepithelial lymphocytes (IEL) has been elicited by several recent reports suggesting that murine and avian intestinal epithelium contains mainly CD3+CD8+ cells expressing the gamma/delta T-cell receptor (TcR) for antigen; this contrasts with systemically distributed T cells which preferentially employ the TcR alpha/beta. An anatomical dichotomy in the distribution of these two T-cell lineages has hence been proposed. Here we report that this concept does not hold true in man. In situ studies with monoclonal TcR-framework antibodies showed that most (70-90%) human intestinal IEL (which are mainly CD3+CD8+) expressed TcR alpha/beta. Moreover, almost half of the intraepithelial CD3+ cells were positive for the smallest (180 kDa) CD45 molecule (UCHL1); this probably reflected that they are antigen-primed and thus represent traditional CD3+CD8+ alpha/beta+ memory T cells.     

Human CD8+ intraepithelial T lymphocytes are mainly CD45RA-RB+ and show increased co-expression of CD45R0 in celiac disease

Expression of various CD45 isoforms (RA, RB and R0) on CD3+, CD4+ and CD8+ intraepithelial and lamina propria T cells was examined in situ by a three-color immunofluorescence technique in jejunal biopsy specimens from 32 patients with celiac disease and 18 controls. The median percentage of CD3+ intraepithelial lymphocytes (IEL) that expressed CD45R0 increased from 52% in controls to 69% in untreated celiac disease (p less than 0.01). Furthermore, the percentages of CD4+ and CD8+ IEL strongly positive for CD45R0 rose respectively from 94% and 24% in controls to 100% and 55% in untreated celiac disease. Conversely, CD45R0 was strongly expressed on most CD3+ lamina propria lymphocytes (LPL) both in control (81%) and diseased (77%-81%) mucosa. A variable fraction of the intraepithelial and lamina propria CD3+ T cells expressed mainly CD45RB (controls, 46% and 20%, respectively; celiac disease, 29% and 15%). Only 2% IEL and 4% LPL were positive for CD45RA. Expression of different CD45R isoforms thus identified three distinct CD8+ T cell subsets in human intestinal mucosa. In addition, our results suggested that antigen-primed CD8+CD45R0+ memory cells accumulate in the jejunal epithelium of patients with untreated celiac disease.     

Subsets of CD3+ (T cell receptor alpha/beta or gamma/delta) and CD3- lymphocytes isolated from normal human gut epithelium display phenotypical features different from their counterparts in peripheral blood

Intestinal intraepithelial lymphocytes (IEL) were studied, after isolation in humans, for their surface antigens with a large variety of monoclonal antibodies. They show peculiar characteristics when compared with peripheral blood lymphocytes and intestinal lamina propria lymphocytes. Although a majority of human intraepithelial lymphocytes (IEL) express an alpha/beta type of T cell receptor (TcR), 13% express a gamma/delta TcR, a percentage which was significantly higher than that found in blood and in lamina propria. In contrast to observations in mice, there was no evidence that normal human TcR gamma/delta+ intestinal IEL might use preferential variable segments of gamma genes. About 10% of human intestinal IEL expressed the alpha chain but not the beta chain of CD8, thus resembling a subset of CD8 alpha+beta- IEL, which was recently described in mice and found to be of thymoindependent origin. In addition, 10% of human IEL had a unique phenotype of immature T cells, as they bore only CD7, but no other T cell or natural killer cell markers. Finally, even the major population of IEL which expressed the usual markers of the T cell lineage (CD3, TcR alpha/beta, CD2, CD4 or CD8 alpha/beta) differed from peripheral blood T lymphocytes by their peculiar expression of surface antigens associated with activation. Indeed, 80% of IEL were CD45R0+, CD45A-, but co-expression of CD11a, CD29 and LFA-3 was inconstant. In addition, 90% of IEL expressed HML-1.     

Lymphocytes bearing the gamma delta T-cell receptor in normal human intestine and celiac disease

Monoclonal antibodies to T-cell receptors were used to investigate the prevalence of the two distinct T-cell subpopulations (TCR alpha beta+ and TCR gamma delta+ cells) in the intestinal mucosa of children with celiac disease (gluten-sensitive enteropathy) as compared with normal intestinal mucosa. TCR gamma delta+ cells were rarely identified in the epithelium of human fetal or normal postnatal intestine and few were present in the lamina propria, whereas the number of distribution of TCR alpha beta+ cells closely resembled that of CD3+ cells. Compared with normal intestine, a significant increase in the number of CD3+, CD8+, TCR alpha beta+, and TCR gamma delta+ intraepithelial lymphocytes was present in celiac disease. Although the mucosal TCR gamma delta+ cells were less numerous than TCR alpha beta+ cells in celiac disease, there was a marked increase in the number of TCR gamma delta+ cells as compared with controls. The ligand recognized by the gamma delta T-cell receptor and the function of these cells have not been determined; however, these findings suggest a possible role for TCR gamma delta+ lymphocytes in mucosal immune responses and tissue injury as seen in celiac disease.     

Sequential appearance of T-cell receptor gamma delta- and alpha beta-bearing intestinal intra-epithelial lymphocytes in mice after irradiation.

We have previously reported that T-cell receptor (TcR) gamma delta-bearing T cells precede TcR alpha beta-bearing T cells in appearance in the thymus after whole-body irradiation. In the present study, the kinetics of appearance of intestinal intra-epithelial lymphocytes (IEL) was examined in mice after whole-body irradiation with a lethal dose of 9.5 Gy or with a sublethal dose of 6 Gy. The number of CD3+ IEL decreased to the lowest value 4 days after irradiation with 9.5 Gy, and thereafter increased to half as many as the normal level by day 7. Thy-1+TcR alpha beta- IEL and Thy-TcR alpha beta- IEL recovered considerably by day 7 after the irradiation, whereas Thy-1+TcR alpha beta+ IEL and Thy-1+TcR alpha beta+ IEL hardly recovered at this stage. All mice died within 12 days after irradiation with a lethal dose of 9.5 Gy. On the other hand, when irradiation dose was decreased to 6 Gy, all mice survived beyond 40 days after irradiation. The number of CD3+ IEL recovered to the normal level by 10 days after irradiation with 6 Gy. Consistently with the results in mice irradiated with a lethal dose, the first cells to increase in IEL of mice irradiated with a sublethal dose were TcR gamma delta+ IEL expressing Thy-1 antigen. The number of Thy-1+TcR gamma delta+ IEL increased to approximately two-fold as many as that in normal mice by day 10, while TcR alpha beta+ IEL began to increase in number from day 20 after irradiation and recovered to the normal level by day 40 after irradiation. Thus, sequential appearance of TcR gamma delta+ and TcR alpha beta+ IEL was evident after irradiation, similar to that seen in the thymus after irradiation. The IEL on day 10 after a sublethal irradiation, which is composed mainly of Thy-1+TcR gamma delta+ IEL, exhibited a strong cytolytic activity against P815 in the presence of anti-CD3 mAb, suggesting that the early appearing Thy-1+TcR gamma delta+ IEL may play important roles in epithelial immunity at an early stage after irradiation.