Immunohistological characterisation of intraepithelial lymphocytes of the human gastrointestinal tract

Hepatic Gα13 ablation shifts region-specific colonic inflammatory status by modulating the bile acid synthetic pathway in mice

Inflammatory bowel disease is defined by inflammation and immune dysregulation. This study investigated the effects of Gα13 liver-specific knockout (LKO) on proximal and distal colons of dextran sodium sulfate (DSS)-induced mice in conjunction with a high-fat diet (HFD). HFD improved body weight gain and disease activity index scores. Gα13LKO exerted no improvement. In the proximal colon, HFD augmented the DSS effect on Il6, which was not observed in Gα13LKO mice. In the distal colon, HFD plus DSS oppositely fortified an increase in Tnfa and Cxcl10 mRNA in Gα13LKO but not WT. Il6 levels remained unchanged. Bioinformatic approaches using Gα13LKO livers displayed bile acid and cholesterol metabolism-related gene sets. Cholic acid and chenodeoxycholic acid levels were increased in the liver of mice treated with DSS, which was reversed by Gα13LKO. Notably, mice treated with DSS showed a reduction in hepatic ABCB11, CYP7B1, CYP7A1, and CYP8B1, which was reversed by Gα13LKO. Overall, feeding HFD augments the effect of DSS on Il6 in the proximal colon of WT, but not Gα13LKO mice, and enhances DSS effect on Tnfa and Cxcl10 in the distal colon of Gα13LKO mice, suggesting site-specific changes in the inflammatory cytokines, potentially resulting from changes in BA synthesis and excretion.

(Not) Home alone: Antigen presenting cell - T Cell communication in barrier tissues

Priming of T cells by antigen presenting cells (APCs) is essential for T cell fate decisions, enabling T cells to migrate to specific tissues to exert their effector functions. Previously, these interactions were mainly explored using blood-derived cells or animal models. With great advances in single cell RNA-sequencing techniques enabling analysis of tissue-derived cells, it has become clear that subsets of APCs are responsible for priming and modulating heterogeneous T cell effector responses in different tissues. This composition of APCs and T cells in tissues is essential for maintaining homeostasis and is known to be skewed in infection and inflammation, leading to pathological T cell responses. This review highlights the commonalities and differences of T cell priming and subsequent effector function in multiple barrier tissues such as the skin, intestine and female reproductive tract. Further, we provide an overview of how this process is altered during tissue-specific infections which are known to cause chronic inflammation and how this knowledge could be harnessed to modify T cell responses in barrier tissue.

The Role of Fusobacterium nucleatum in Colorectal Carcinogenesis

Colorectal cancer (CRC) is one of the most frequent and deadly neoplasms worldwide. Genetic factors, lifestyle habits, and inflammation are important risk factors associated with CRC development. In recent years, growing evidence has supporting the significant role of the intestinal microbiome in CRC carcinogenesis. Disturbances in the healthy microbial balance, known as dysbiosis, are frequently observed in these patients. Pathogenic microorganisms that induce intestinal dysbiosis have become an important target to determine the role of bacterial infection in tumorigenesis. Interestingly, the presence of different bacterial strains, such as Fusobacterium nucleatum, has been detected in tissue and stool from patients with CRC and associated with substantial clinical and molecular features, as well as with patient therapy response. Therefore, understanding how the presence and levels of F. nucleatumstrains in the gut affect the risk of CRC onset and progression may inform suitable candidates for interventions focused on modulation of this bacteria. Here we review new insights into the role of gut microbiota in CRC carcinogenesis and the clinical utility of using the detection of F. nucleatum in different settings such as screening, prognosis, and microbiota modulation as a means to prevent cancer, augment therapies, and reduce adverse effects of treatment.

Up-regulation of syndecan-2 in proximal colon correlates with acute inflammation

We previously reported that syndecan-2 expression is increased on the colonic epithelium during chronic inflammation. Here, we report that syndecan-2 exhibits a different pattern of site-specific colonic expression during acute inflammation. Syndecan-2 expression was up-regulated predominantly in the proximal colon of dextran sulfate sodium-induced colitis mice. The colitis-associated up-regulation of syndecan-2 was barely detected in Rag-1^-/- (recombination activating gene 1 knockout) mice under colitis-inducing conditions. Increased syndecan-2 expression correlated with increased levels of infiltrated CD4⁺ IL-17A⁺ T cells in the proximal colon. Serum levels of IL-17A were increased during the acute inflammatory response in normal mice but not Rag-1^-/- mice. IL-17A directly induced IL-17 receptor (IL-17RA) and syndecan-2 expression in ex vivo-cultured proximal colon tissues and adenoma cell lines from proximal colon. IL-17RA knockdown reduced the IL-17A-mediated syndecan-2 expression in SNU1235 cells. No elevation of syndecan-2 or IL-17RA was observed in colonic tissues from IL-17A^-/- mice during colitis induction. Finally, increased expression of syndecan-2 and IL-17RA was observed in the proximal colons of cecal ligation and puncture-induced sepsis mice and infectious pan colitis patients. Together, these data suggest that acute inflammation induces syndecan-2 expression predominantly in the proximal colon via IL-17A-IL-17RA signaling during the early stage of the inflammatory response and that proximal colonic syndecan-2 might be a biomarker for acute inflammation.-Hong, H., Song, H.-K., Hwang, E. S., Lee, A. R., Han, D. S., Kim, S.-E., Oh, E.-S. Up-regulation of syndecan-2 in proximal colon correlates with acute inflammation.

The predictive effect of primary tumour location in the treatment of metastatic colorectal cancer: a Canadian consensus statement

In recently published data, the predictive value of primary tumour location for the treatment of metastatic colorectal cancer with available biologic therapies has been explored. Recognizing the potential effect of those data on clinical practice, we convened a meeting of Canadian experts who treat metastatic colorectal cancer to develop a set of national, evidence-based treatment guidelines based on primary tumour location. This report summarizes the relevant evidence and presents the consensus recommendations of those experts.

Association Between Prognosis and Tumor Laterality in Early-Stage Colon Cancer

IMPORTANCE

Recent data have suggested that disease biology and outcome of colon cancer may differ between right-sided and left-sided tumors. However, the literature on the prognostic value of tumor laterality is conflicting.

OBJECTIVE

To explore differences in laterality based on disease characteristics and outcomes in a population-based cohort of early-stage colon cancer.

DESIGN, SETTING, AND PARTICIPANTS

This investigation was a population-based retrospective cohort study of patients with early-stage colon cancer from the province of Ontario, Canada. Electronic records of treatment were linked to the Ontario Cancer Registry to identify all patients with colon cancer who underwent resection between January 1, 2002, and December 31, 2008. The date of the final analysis was October 20, 2016. The study population included a 25% random sample of all patients with resected stage I to III disease. Right-sided colon cancer was defined as any tumor arising in the cecum, ascending colon, hepatic flexure, or transverse colon. Left-sided colon cancer was defined as any tumor arising in the splenic flexure, descending colon, sigmoid colon, or rectosigmoid colon.

MAIN OUTCOMES AND MEASURES

Overall survival (OS) and cancer-specific survival (CSS) measured from the time of resection.

RESULTS

This study identified 6365 patients with early-stage colon cancer (48.7% [3098 of 6365] female). Their median age was 72 years, and 51.7% (3291 of 6365) had right-sided disease. Stage distribution was 18.3% (1163 of 6365) stage I, 38.4% (2446 of 6365) stage II, and 43.3% (2756 of 6365) stage III. Patients with right-sided colon cancer were more likely to be older (median age, 73 vs 70 years; P < .001) and female (54.4% [1790 of 3291] vs 42.6% [1308 of 3074], P < .001) and have greater comorbidity. Right-sided cancers were more likely to be T4 (19.2% [631 of 3291] vs 15.9% [490 of 3074], P < .001) and poorly differentiated (21.1% [695 of 3291] vs 9.6% [295 of 3074], P < .001) but less likely to be node positive (42.0% [1383 of 3291] vs 44.7% [1373 of 3074], P = .03) compared with left-sided disease. In adjusted analyses, there was no difference in long-term survival for right-sided compared with left-sided colon cancer: the hazard ratios were 1.00 (95% CI, 0.92-1.08) for OS and 1.00 (95% CI, 0.91-1.10) for CSS. These results were consistent when the survival analyses were restricted to stage III disease: the hazard ratios were 1.03 (95% CI, 0.93-1.14) for OS and 1.10 (95% CI, 0.97-1.24) for CSS.

CONCLUSIONS AND RELEVANCE

In this population-based cohort of early-stage resected colon cancer, disease laterality was not associated with long-term OS or CSS.

Evaluation of the left-to-right shift of colon tumors in Iran: Is the trend changing?

Background:

Colorectal cancer (CRC) is the second cause of cancer-related deaths worldwide. There have been several studies reporting the proximal tumor shift, especially in Western countries. In the present study, we investigated the clinicopathologic and anatomical distributions of colorectal tumors in Iranian CRC patients.

Materials and Methods:

In this retrospective cohort study, 258 patients with CRC from 2008 to 2013 were evaluated. Comparison of variables was performed using Pearson's chi-square test and Fisher's exact test depending on the nature of the data.

Results:

A total of 258 patients including 124 (48.1%) females and 134 (51.9%) males enrolled in this study. The majority of cancers were detected in the rectosigmoid, i.e., 98 (38%) followed by the left colon, i.e., 84 (32.6%) and the right colon, i.e., 76 (29.5%). In the present study, we observed the significant association between metastases, adjuvant therapy, family history, and history of inflammatory bowel disease (IBD) with tumor, node, and metastasis (TNM) staging (P < 0.001). In univariate analysis, there was a strong association between overall survival (OS) and stage II CRC (P = 0.03). However, the predictive value was lost in multivariate analysis (P = 0.145).

Conclusion:

Unlike the majority of previous studies on Iranian CRC patients, we observed a considerably higher occurrence of right-sided colon cancers (84 versus 76). Although this phenomenon did not reach the statistical significance rate, based on recent studies on Iranian population including the present one, the pattern of anatomical distribution of colorectal tumors has been changed toward the proximal colon. This requires an urgent need to provide other strategies and complementary detecting approaches in order to identify proximal tumors in Iranian CRC patients.

Is right-sided colon cancer different to left-sided colorectal cancer? - a systematic review

Colorectal cancer (CRC) exhibits differences in incidence, pathogenesis, molecular pathways and outcome depending on the location of the tumor. This review focuses on the latest developments in epidemiological and scientific studies, which have enhanced our understanding on the underlying genetic and immunological differences between the proximal (right-sided) colon and the distal (left-sided) colorectum. The different ways in which environmental risk factors influence the pathogenesis of CRC depending on its location and the variations in surgical and oncological outcomes are also discussed in this review. In the current era of personalized medicine, we aim to reiterate the importance of tumor location in management of CRC and the implication on future clinical and scientific research.

Regional specialization within the intestinal immune system

The intestine represents the largest compartment of the immune system. It is continually exposed to antigens and immunomodulatory agents from the diet and the commensal microbiota, and it is the port of entry for many clinically important pathogens. Intestinal immune processes are also increasingly implicated in controlling disease development elsewhere in the body. In this Review, we detail the anatomical and physiological distinctions that are observed in the small and large intestines, and we suggest how these may account for the diversity in the immune apparatus that is seen throughout the intestine. We describe how the distribution of innate, adaptive and innate-like immune cells varies in different segments of the intestine and discuss the environmental factors that may influence this. Finally, we consider the implications of regional immune specialization for inflammatory disease in the intestine.

Significance of intraepithelial lymphocytosis in small bowel biopsy samples with normal mucosal architecture

OBJECTIVES

The aim of this study was to determine the specificity of increase in intraepithelial lymphocytes (IELs) with normal villous architecture in small bowel biopsy samples for diagnosis of gluten sensitivity (GS) and its significance in the absence of GS.

METHODS

Small bowel biopsy samples from 43 patients with increased IELs and no other pathology were reviewed. Patients with prior diagnosis of GS were excluded. A group of 46 patients with normal duodenal biopsy during the same period served as controls. The clinical records of patients and controls were examined for presenting symptoms, laboratory tests, and final clinicopathological diagnosis. Immunohistochemical characterization of IELs was performed in 13 cases.

RESULTS

Four (9.3%) patients had GS based on positive IgA antiendomysial antibodies (n = 3) and favorable response to gluten-free diet (n = 4). One patient (2.2%) had partially treated tropical sprue; six patients (14%) had disorders of immune regulation including Hashimoto's thyroiditis (n = 2) and one case each of Graves' disease, rheumatoid arthritis, psoriasis, and multiple sclerosis; and six patients (14%) were on nonsteroidal anti-inflammatory drugs (NSAIDs). In contrast, none of the control subjects had GS (p = 0.05), tropical sprue, or immunoregulatory disorders (p = 0.011), and one (2.2%) was on NSAIDs (p = 0.04). Increased IELs were also observed in Crohn's disease, lymphocytic/collagenous colitis, and bacterial overgrowth, but the association did not reach statistical significance. Histological features (number and distribution of IELs, crypt mitoses) and immunophenotypic analysis of IELs did not reliably distinguish GS-related from non-GS-related causes of increased IELs.

CONCLUSIONS

Intraepithelial lymphocytosis in an otherwise normal small bowel biopsy is somewhat nonspecific, but in nearly 10% of cases can be the initial presentation of GS. Therefore all patients with this finding should be investigated for GS. Increased IELs may also be associated with autoimmune disorders and NSAIDs.

Combined intrarectal/intradermal inoculation of recombinant Mycobacterium bovis bacillus Calmette-Guérin (BCG) induces enhanced immune responses against the inserted HIV-1 V3 antigen

The development of a successful recombinant Mycobacterium bovis bacillus Calmette-Guérin (rBCG) vector-based vaccine for human immunodeficiency virus type 1 (HIV-1) requires the induction of high levels of HIV-1-specific immunity while at the same time maintaining immunity to tuberculosis. To examine a combined vaccination strategy for enhancement of immune responses specific for HIV-1, guinea pigs were inoculated with either a single or combination intradermal (i.d.), intrarectal (i.r.) and intranasal (i.n.) administration of rBCG-pSOV3J1 which secretes a chimeric protein of HIV-1 V3J1 peptide and alpha-antigen. Significant level of delayed-type hypersensitivity to both V3J1 peptide and tuberculin was induced in guinea pigs inoculated with human doses of rBCG-pSOV3J1 by a combination of intrarectal and intradermal routes. Guinea pigs inoculated by combined routes also had significantly higher titers of HIV-1-specific serum IgG and IgA compared with those animals immunized only intrarectally, which led to the enhanced neutralization activity against HIV-1(MN). In addition, the induction of high levels of IFNgamma and interleukin-2 (IL-2) mRNA in PBMC, splenocytes, and intraepithelial lymphocytes from the immunized animals was detected until at least 110 weeks post-inoculation. These results suggest that enhanced immune responses specific for HIV-1 are efficiently induced by combined intrarectal and intradermal immunization with rBCG-HIV, and antigen-specific Th1-type memory cells are maintained for more than 2 years in the immunized animals. Thus, inoculation with rBCG-HIV by combined routes represents an effective vaccination strategy to elicit high levels of HIV-1-specific immune responses.

The gut-associated lymphoid tissues of the northern brown bandicoot (Isoodon macrourus)

The gut associated lymphoid tissues (GALT) of a juvenile bandicoot has been examined using histological and immunohistochemical techniques. The mesenteric lymph nodes were hyperfollicular and had well defined paracortical and medullary areas. Lymphocytes were densely packed throughout the cortex and paracortex and the mantles of the follicles. The GALT contained two distinct areas of tissue organisation. One consisted of large areas of aggregated follicles, whilst the other consisted of more linearly distributed follicles. The distribution of T and B cells in the tissue beds was documented using antibodies to surface markers CD3, CD5 and CD79b. T-cells were present in high numbers in the cortical region of the lymph node, whilst B-cells were predominant in the mantle of the follicles. Dispersed CD3 positive T-cells were abundant in the villi lacteals and present in high numbers in follicular areas of gut. CD79b positive B-cells were not observed in the lacteals but were abundant in the mantles of follicles. This is similar to that observed in other metatherians.

The terminal ileum is affected in patients with lymphocytic or collagenous colitis

Lymphocytic colitis (LC) and collagenous colitis (CC) are diseases characterized by the presence of marked intraepithelial lymphocytosis. Both of these disorders affect primarily the colon. However, involvement of the distal small intestine has not been systematically studied. The purpose of this study was to evaluate the type and degree of intraepithelial lymphocytosis in the terminal ileum of patients with LC or CC. Terminal ileal mucosal biopsies from 22 patients with LC (male/female ratio 0.22, mean age 47 years) and 23 with CC (male/female ratio 0.43, mean age 54 years) were evaluated for the number of intraepithelial lymphocytes (IEL) per 100 epithelial cells (EC) both in the villi and crypts. The results were compared with 30 patients with inflammatory bowel disease (16 with Crohn's disease [CD], 14 with ulcerative colitis [UC]) and 24 patients (male/female ratio 0.33, mean age 44 years) without colonic pathology as normal controls. None of the patients had celiac sprue. Paired terminal ileum and colonic mucosal biopsies from 6 patients with LC, 4 with CC, 5 with CD, 5 with UC, and 10 normal controls were also immunohistochemically stained with monoclonal antibodies to CD3, CD8, CD20, and a class II MHC antigen (LN3-HLA-DR). In the villi the IEL count/100 EC was 11.8 +/- 1.8 in LC and 10.3 +/- 1.9 in CC (p = 0.3). These values were both significantly higher than in CD (2.8 +/- 0.4, p <0.001), UC (3.1 +/- 0.4, p <0.001), or normal controls (2.2 +/- 0.2, p <0.001). In the crypts the IEL count was 3.8 +/- 0.5 in LC and 3.2 +/- 0.5 in CC (p = 0.3). These values were also significantly higher than in CD (2.3 +/- 0.4, p = 0.02), UC (2.1 +/- 0.3, p = 0.02), or normal controls (1.5 +/- 0.2, p <0.001). The presence of >5 IELs/100 EC in terminal ileum biopsies was highly specific for LC and CC (specificity 98%, sensitivity 73% and 56% for LC and CC, respectively). The IEL phenotype was similar in all groups of patients and in the ileum and colon of individual patients. Intraepithelial lymphocytes were CD3+, CD8+, CD20-, and LN3-HLA-DR-, indicative of a suppressor T-cell phenotype. Intraepithelial lymphocytosis occurs in the terminal ileum in patients with LC or CC and may be helpful in diagnosing these conditions and distinguishing LC or CC from CD or UC in diagnostically difficult cases. The results suggest that the terminal ileum may be involved by a similar pathogenic process as the colon in LC and CC.

Characterization of lymphocyte subsets from mucosal tissues in neonatal swine

Monitoring differences in lymphocytes during neonatal development constitutes a key to understanding the developing piglet's natural and pathological immune responses. A survey was conducted to accumulate information on the phenotype of lymphocytes isolated from blood, lymph nodes, and lymphoid associated structures of the pig small intestine of conventional pigs from day 1 to 47 of age and inbred miniature pigs between 12 and 82days. The effect of weaning, and age before and after weaning, were also evaluated. Weaning had a significant effect on the number of CD4(+), CD8(+), double positive CD4(+)/CD8(+), CD21(+), deltagammaTCR(+), SWC3(+) and SLA-DQ(+) cells. Aging of the pig before and after weaning resulted in significant changes in lymphocytes isolated from mesenteric lymph nodes and ileal sites. These results constitute an important baseline for studying mucosal immune response of neonatal pigs and identifying factors that influence the ability of the neonate to respond to the stresses and antigenic exposure associated with weaning.

The nature of the myenteric infiltrate in achalasia: an immunohistochemical analysis

Achalasia is an esophageal motor disorder characterized by abnormal relaxation of the lower esophageal sphincter and absence of progressive peristalsis in the esophageal body. Previous studies evaluating esophagomyotomy and esophageal resection specimens have shown the presence of myenteric inflammation to be a consistent and early pathologic change in patients with achalasia. Thus, the goal of this study was to determine the immunohistochemical characteristics of the inflammatory infiltrate within the myenteric plexus in patients with clinically early and end-stage achalasia. Using formalin-fixed tissue, we analyzed the immunohistochemical features of the myenteric lymphocytes using antibodies that recognize B cells (CD20), T cells (CD3), T cell subsets (CD8), and the activation state of T cell subpopulations (TIA-1 and granzyme B) in nine patients with clinically early achalasia who underwent esophagomyotomy and 13 patients with clinically endstage achalasia who underwent esophageal resection. The myenteric infiltrate in all nine esophagomyotomy specimens was composed predominantly of T cells (CD3-positive), the majority of which also stained for CD8. In five of nine specimens, the majority of CD8-positive cells stained for TIA-1. In the esophageal resection specimens, the myenteric infiltrate was composed predominantly of CD3-positive T cells in seven of 13 cases. In three cases, there was a predominance of CD20-positive B cells, and in the remaining three cases there were relatively equal numbers of T and B cells. In eight of 13 cases, the majority of T cells stained for CD8. TIA-1 immunoreactivity was found in the majority of CD8-positive cells in nine of 13 cases. In all esophagomyotomy and esophageal resection specimens studied, rare granzyme B-positive cells were detected. In conclusion, the majority of myenteric inflammatory cells in patients with achalasia are CD3-positive T cells, most of which are also CD8-positive, although the relative percentage of such cells appears to decrease with disease progression. Furthermore, many of the CD3-positive/CD8-positive myenteric lymphocytes also express TIA-1, suggesting they are resting or activated cytotoxic T cells. The immunohistochemical demonstration of granzyme B in a subpopulation of these cells supports the contention that achalasia is an immune-mediated disease, although the inciting antigen remains an enigma.

Digestive System 1

This chapter deals with the digestive system. The major and minor salivary glands and their secretions also represent and integral part of the protective mechanism of the oral cavity, and derangement of saliva production may lead to loss of integrity of the oral mucosa. Drug-induced abnormalities of taste sensation are also well-described phenomena occurring in man although human studies are necessary for the detection of these effects. Inflammation of the oral cavity may involve the buccal mucosa, the gingiva (gingivitis), the tongue (glossitis), and the peridontal tissues (peridontitis). Therapeutic agents can induce inflammatory lesions in the tongue. Moreover, a protective layer of mucus, a visco-elastic material containing high molecular weight glycoproteins produced by the major and minor salivary glands, covers the stratified squamous mucosa of the oral cavity. Salivary secretions also possess digestive enzyme activity although in herbivores and carnivores, it is usually low in contrast to high digestive enzyme activity in omnivorous species.

Evaluation of B and T lymphocytes and plasma cells in colonic mucosa from healthy dogs and from dogs with inflammatory bowel disease

The aim of this study was to investigate the subpopulations of lymphocytes in the colonic mucosa of healthy dogs and dogs with inflammatory bowel disease (IBD). Fourteen normal dogs and 13 dogs with IBD were examined. Endoscopic biopsy specimens of colonic mucosa from each dog were stained specifically for pan T lymphocytes (CD3) and pan B lymphocytes (CD79a), and for plasma cells with methyl green pyronin (MGP) stain. Cells were counted by means of a grid and statistical analysis was performed on the data collected. B and T lymphocytes were also counted in the glandular epithelium of normal dogs and dogs with IBD and the normal and abnormal groups compared statistically. Healthy dogs had significantly lower numbers of T cells in the lamina propria and glandular epithelium and significantly lower numbers of B cells in the lamina propria. Significant group differences for plasma cells were not evident. Our results indicate that in IBD a chronic cellular immune reaction is present in the diseased gut involving increased numbers of B and T lymphocytes.

Quantitative and qualitative immunohistochemistry of T cell subsets and MHC class II expression in the canine small intestine

In man and rodents, cells of the gastrointestinal immune system include B and T lymphocytes, granulocytes, macrophages and dendritic cells. Abnormalities in leucocyte numbers and function have been described in diseases of humans, such as coeliac disease and inflammatory bowel disease. The purpose of this study is to describe the normal distribution of T cells and MHC Class II expression in the small intestine of clinically normal dogs, to allow subsequent comparison with disease states. Full-thickness sections of duodenum, jejunum and ileum from seven young adult beagle dogs were immediately snap-frozen following euthanasia. Avidin-biotin-enhanced immunocytochemistry was used to detect expression of canine CD3, CD4, CD8 and MHC Class II antigens. Positively stained lamina propria cells were quantified using an eyepiece graticule, and positively stained intraepithelial cells by counts per 100 epithelial cells. In the lamina propria, the density of all leucocyte subsets was significantly increased towards the villus tip for all regions (p < 0.05). There was no apparent difference in the distribution of CD3+, CD4+ and CD8+ leucocytes between the three portions of the small intestine. The ratios of CD4+ cells to CD8+ cells in the lamina propria and epithelium were 59:41 and 15:85, respectively. Subtractive analysis suggested that 50-55% of CD3+ intraepithelial cells were CD4-CD8-. MHC Class II expression was apparent upon lamina propria cells with a dendritic morphology, as well as round cells. Epithelial MHC Class II expression was apparent in 7/7 ileal sections, compared with only 1/7 duodenal and 1/7 jejunal sections. This study shows that the small intestinal mucosa of the dog contains similar leucocyte populations to those found in other species, and suggests that these cells may play similar roles in gastrointestinal immunity.

Intraepithelial lymphocytes in normal human intestine do not express proteins associated with cytolytic function

Human small intestine contains a very large population of intraepithelial T lymphocytes (IELs) that are oligoclonal, appear functionally to be cytolytic T cells, and may contribute to the normal and pathological turnover of intestinal epithelial cells. This report addresses the cytolytic function of IELs in normal small intestine by examining their expression of molecules that carry out cell-mediated cytolysis. Immunohistochemical analyses of granzyme B, perforin, Fas ligand, and tumor necrosis factor-alpha demonstrated these proteins were not expressed by small intestinal IELs in situ. These proteins also were not expressed by colonic IELs or by lamina propria lymphocytes in the small or large intestine. Granzyme A, however, was expressed by a large fraction of IELs. In contrast to these in situ results, isolated and in vitro activated IELs were shown to express effector proteins consistent with cytolytic T cells, including granzyme B, Fas ligand, tumor necrosis factor-alpha, and interferon-gamma. These results are most consistent with the vast majority of IELs in normal human small intestine being resting cytolytic T cells and suggest that these cells do not contribute to the apoptotic cell death of epithelial cells in normal intestine.

Characterization of a 180-kDa intestinal epithelial cell membrane glycoprotein, gp180. A candidate molecule mediating t cell-epithelial cell interactions

Previous studies have shown that normal human intestinal epithelial cells stimulate CD8(+) suppressor T cell proliferation in an allogeneic mixed epithelial/T cell co-culture system, which is neither restricted by class I or class II major histocompatibility complex antigens nor by any soluble factors from epithelial cells. Two epithelial specific monoclonal antibodies (mAb), mAb B9 and mAb L12, are potent inhibitors of this mixed epithelial/T cell reaction but not of conventional mixed lymphocyte reactions. While phenotypically distinct by tissue staining, both mAbs recognize a 180-kDa epithelial membrane glycoprotein (gp180). Further characterization of gp180 revealed the following. 1) The protein migrated between 150 and 180 kDa in SDS-polyacrylamide gel electrophoresis and could be resolved by Western blot using mAb B9 or mAb L12. 2) The molecule has two forms, an apically sorted glycosylphosphatidylinositol-anchored form and a basolateral transmembrane form. 3) gp180 is heavily N-glycosylated, since N-glycanase treatment results in a >50% reduction in size. 4) Purified gp180 can bind to peripheral blood T cells and activate p56(lck). 5) gp180 can activate p56(lck) in 3G8 (a murine T cell hybridoma transfected with human CD8alpha cDNA) but not in 3G4 (CD4 transfectant), suggesting that gp180 binds to CD8. Thus, gp180 appears to be a novel regulator of mucosal immune responses.

Class II MHC expression on rat intestinal intraepithelial lymphocytes

The expression of class II major histocompatibility complex (MHC) on rat intestinal intraepithelial lymphocytes (IELs) and mesenteric lymph node cells (MLNCs) were examined by immunofluorescence and flow cytometry. As expected, MLNCs contain eight small populations of CD4+ class II MHC+ T-cells in addition to classical antigen presenting cells. In contrast, rat IELs include a significant population of class II MHC+ T-cells, predominantly in the CD8+ CD4-alpha beta TCR+ subset. IEL samples with a relatively high percentage of class II MHC+ cells also include some CD4+ class II MHC+ cells; IEL samples with a low percentage of class II MHC+ cells also include some CD4- CD8- class II MHC+ cells. The role of lymphocyte subpopulations in the intestinal epithelium may need to be revisited in consideration of these findings.

Phenotypic characterization of T cells infiltrating the conjunctiva in chronic allergic eye disease

BACKGROUND

Chronic allergic conjunctivitis comprises a spectrum of diseases including atopic keratoconjunctivitis, atopic blepharoconjunctivitis, vernal keratoconjunctivitis, and contact lens-associated giant pupillary conjunctivitis. Each condition is characterized by a complex immunopathology with a mixed cellular infiltrate. Treatment with conventional mast cell stabilizers is often unsatisfactory, and therapy depends heavily on topical corticosteroids.

OBJECTIVE

Recent evidence suggests that T lymphocytes play an important role in mediating the immunopathology seen in the chronic allergic response in the skin and the lungs.

METHODS

We have therefore investigated the prevalence of T cells and their subsets in the different chronic allergic eye conditions by means of immunohistochemistry.

RESULTS

We found significantly increased numbers of CD4+, CD45RO+, and HLA-DR+ T cells in the conjunctiva of patients with atopic and vernal keratoconjunctivitis and giant papillary conjunctivitis, with a corresponding upregulation of markers present on antigen presenting cells.

CONCLUSIONS

These findings suggest that like allergic conditions in the skin and lungs, CD4+ memory T cells are involved in the regulation of the immunopathology of chronic allergic eye responses. Further characterization of these T cells will provide the information necessary for future immunotherapeutic interventions.

Gastric and esophageal intraepithelial lymphocytes in pediatric celiac disease

Celiac disease (CD) is associated with marked mononuclear cell inflammation in the small intestinal mucosa. This study was performed to evaluate analogous changes in the gastric and esophageal mucosa of pediatric patients with CD, with emphasis on epithelial lymphocytosis. We evaluated intraepithelial lymphocytes (IELs) in 23 gastric (no.IELs/100 epithelial cells) and 14 esophageal mucosal biopsy specimens (IELs/hpf) from 23 pediatric cases of CD and 10 nonceliac matched controls. Four patients had postgluten withdrawal biopsy specimens reviewed, and one of these had further postgluten challenge biopsy specimens evaluated as well. Gastric specimens from the CD cases showed a significantly increased IEL count (20.5 +/- 14.4; range, 4-50) compared to controls (3.4 +/- 1.9; range, 1-8; p < 0.001), which also correlated directly with the histologic severity of the small intestinal disease as assessed by the degree of villous shortening. Sixteen (69.5%) of 23 gastric specimens showed > 8 IELs, which was the highest value obtained in control specimens. The four posttreatment specimens showed a significant reduction in the gastric IEL counts from a mean of 19.8 to 3.5 IELs/100 epithelial cells (p < 0.001). The single case that had a further postgluten challenge biopsy showed a return to the pregluten withdrawal IEL count. However, the degree of gastric intraepithelial lymphocytosis did not correlate with any of the clinical data, such as age, gender, presenting symptoms, or serum antibody levels (antigliadin, antireticulin, or antiendomysium). Furthermore, no differences were observed in the IEL count in CD esophageal specimens (5.3 +/- 2.6; range, 2-10) compared to controls (5.2 +/- 1.5; range, 3-8; p = 0.935). These findings suggest that an immune-mediated lymphocytic response linked to gluten occurs in the gastric epithelium, similar to that seen in the small intestine of pediatric patients with CD. Therefore, gastric intraepithelial lymphocytosis may represent a concurrent manifestation of CD rather than a separate entity in the pediatric population.

Phenotypic and functional assessment of intraepithelial lymphocytes (IEL) isolated from rat colon and small bowel

We have compared the proliferative potential of IELs isolated from rat colon (CIEL) and small bowel (SBIEL), and compared this with that observed using spleen lymphocytes. Unless additional irradiated spleen cells were added as a source of accessory cells, both IEL populations show poor proliferation in response to Con A stimulation. The CD4/CD8 ratio in spleen, SBIEL and CIEL was markedly different (3:1, 1:3, and 1:1, respectively). Cells expressing surface markers characteristic of macrophages were not routinely found in SBIELs. Both IEL preparations inhibited spleen cell proliferation in response to Con A or immobilized anti-CD3, and produced a soluble factor(s) capable of causing similar inhibition. For CIEL this inhibition was dependent upon a proliferation-independent but cell-cell contact dependent event.

Histological and immunohistological investigation of alimentary tract lymphoid tissue in the koala (Phascolarctos cinereus), brushtail possum (Trichosurus vulpecula) and ringtail possum (Pseudocheirus peregrinus)

The histological appearance and distribution of T cells, B cells and plasma cells were investigated for oropharyngeal tonsils, small intestinal lymphoid aggregations (Peyer's patches), caecocolic lymphoid patches and mesenteric lymph nodes of koalas (Phascolarctos cinereus), common brushtail possums (Trichosurus vulpecula) and common ringtail possums (Pseudocheirus peregrinus). The histological organisation and distribution of lymphoid cell subpopulations of these tissues were similar to those described in eutherian mammals, although some differences were found in comparison with previous descriptions of American opossum tissues. The main variation among the 3 species was in the structural organisations of the oropharyngeal tonsil and the caecocolic lymphoid patch which were more complex in the koala than in possums. In the koala the extensive crypts of the oropharyngeal tonsils and folding of the mucosa of the caecocolic lymphoid patch increased their surface area and, in addition, both structures had areas of epithelium heavily infiltrated with T and B cells. These features could indicate that these structures are important in immunological surveillance of orally presented antigens in koalas.

Evidence against T-cell development in the adult human intestinal mucosa based upon lack of terminal deoxynucleotidyltransferase expression

Several lines of evidence indicate that a subset of murine intestinal intraepithelial lymphocytes (iIEL), particularly those which express the CD8 alpha alpha homodimer, mature extrathymically. This study confirms that a small fraction of adult human iIEL also express the CD8 alpha alpha homodimer and demonstrates that most of these cells in the small intestine are T cells using the alpha beta T-cell receptor (TCR). Whether these cells or other subsets of adult human iIEL mature extrathymically in the intestine was assessed by measuring the expression of terminal deoxynucleotidyltransferase (TdT), an enzyme expressed exclusively by immature lymphocytes. Very low levels of TdT message could be detected by polymerase chain reaction (PCR) amplification in some iIEL samples. The level of TdT expression was assayed by competitive PCR amplification and compared with thymocytes and peripheral blood lymphocytes. These measurements indicated that the number of immature T cells expressing TdT in the intestinal epithelium was less than one cell per 10(7) lymphocytes. This demonstrates that there are few if any TdT expressing immature T cells in the adult human intestinal mucosa and indicates, therefore, that T-cell development in the intestinal mucosa does not contribute significantly to the T-cell repertoire of the adult human intestine.

Intraepithelial and lamina propria leucocyte subsets in inflammatory bowel disease: an immunohistochemical study of colon and rectal biopsy specimens

AIMS

To gain new insights into the pathogenesis and differential diagnosis of ulcerative colitis and colonic Crohn's disease.

METHODS

Immunohistochemistry for different leucocyte subsets was performed in biopsy specimens of the sigmoid colon and rectum from 55 patients with inflammatory bowel disease and 11 healthy controls.

RESULTS

Colonic biopsy specimens from patients with active ulcerative colitis had significantly higher numbers of CD45+ and CD3+ leucocytes compared with those from patients with inactive disease, and higher numbers of total leucocytes and macrophages than those from patients with Crohn's disease. Rectal biopsy specimens from patients with Crohn's disease had greater numbers of intraepithelial leucocytes (CD45, CD3 and CD8 cells) than specimens from patients with active or inactive ulcerative colitis, or from healthy controls.

CONCLUSIONS

Because of the phenotypic differences in the inflammatory infiltrate in the mucosa from the sigmoid colon and the rectum, the segment of the intestine to be biopsied should be specified. Assessment of the leucocytic component of the intraepithelial infiltrate in rectal biopsy specimens was more useful than examination of colonic biopsy specimens in the differential diagnosis of ulcerative colitis and Crohn's disease.

Distinct structural and functional epitopes of the alpha E beta 7 integrin

Intestinal intraepithelial lymphocytes (iIEL) are predominantly CD3+, CD8+ T lymphocytes located above or adjacent to the mucosal basement membrane. Although they are positioned to interact with intercellular luminal antigen or with enterocytes, the function of iIEL remains unknown. Most (> 85%) of the iIEL express the alpha E beta 7 integrin which appears to be involved in the adhesion of lymphocytes to epithelial cells. We report the characterization of three monoclonal antibodies (mAb) termed alpha E7-1, alpha E7-2, and alpha E7-3, that react with the alpha E beta 7 integrin recognized by the previously described mAb HML-1 as demonstrated by identical sodium dodecyl sulfate-polyacrylamide gel electrophoresis mobility and charge. Flow cytometric analysis of antibody cross-blocking indicated that these mAb recognize distinct epitopes of alpha E beta 7. While all of the mAb were capable of blocking the adhesion of cultured iIEL to a breast epithelial cell line, only HML-1 and alpha E7-1 (which recognize an identical or closely related epitope) were co-stimulatory with suboptimal concentrations of anti-CD3 mAb in inducing proliferation of cultured iIEL. Thus, these mAb appear to recognize functionally distinct epitopes of alpha E beta 7 and will be useful to study relationships between the structure and function of this integrin.

An in vitro model for immune control of chlamydial growth in polarized epithelial cells

A polarized epithelial culture system and chlamydia-specific T-cell lines and clones were employed to investigate the ability and mechanisms by which T cells control the growth of chlamydiae in epithelial cells. Monolayers of polarized mouse epithelial cells were infected with the Chlamydia trachomatis agent of mouse pneumonitis (MoPn) and then exposed to antigen-stimulated MoPn-specific T-cell lines and clones. The results revealed that in vivo-protective MoPn-specific T-cell lines and clone 2.14-0 were capable of inhibiting the growth of MoPn in polarized epithelial cells. In contrast, the nonprotective MoPn-specific T-cell clone 2.14-3, naive splenic T cells, and a control T-cell clone could not inhibit the growth of MoPn in epithelial cells. Transmission electron microscopic analysis of infected epithelial cells which were exposed to clone 2.14-0 confirmed the absence of an established infection, as deduced from the virtual absence of inclusions in the cells. Antigen-specific activation of clone 2.14-0 was required for the MoPn-inhibitory function, since the absence of antigenic stimulation or stimulation with a heterologous chlamydial agent did not result in MoPn growth inhibition. Activation of clone 2.14-0 resulted in acquisition of the capacity to inhibit growth of both homologous (MoPn) and heterologous chlamydial agents. Close interaction between epithelial cells and clone 2.14-0 was required for the MoPn-inhibitory action, because separation of the cell types by a filter with a pore size of 0.45, 3.0, or even 8.0 microns abrogated MoPn inhibition. Protective T cells may act at close range in the epithelium to control chlamydial growth, possibly involving short-range-acting cytokines. The ability of antigen-stimulated T-cell lines and clones to inhibit chlamydial growth in polarized epithelial cultures could be a useful method for identifying protective T-cell clones and antigenic peptide fragments containing protective epitopes.

Increased macrophage subset in inflammatory bowel disease: apparent recruitment from peripheral blood monocytes

Mucosal specimens from active Crohn's disease (ileum, n = 6; colon, n = 6), active ulcerative colitis (n = 9), normal ileum (n = 6), and normal colon (n = 6) were subjected to paired immunofluorescence staining for characterisation of macrophage subsets in situ. In the normal state, only few CD68+ macrophages (< 10%) expressing the myelomonocytic L1 antigen (calprotectin) were seen. In inflamed mucosa, especially near small vessels, the CD68+L1+ fraction increased with the degree of inflammation, near ulcers to median 65% (range 35-91%). Cells reactive with the monoclonal antibody RFD7 were also increased in inflammation but less than 5% of them costained for L1 antigen. It is concluded that L1 producing macrophages are distinct from the RFD7+ subset and probably recently recruited from peripheral blood monocytes. Like granulocytes, L1+ macrophages may be important in non-specific defence, providing calprotectin with putative anti-microbial and anti-proliferative properties.

Postnatal development of intra-epithelial leukocytes in the chicken digestive tract: phenotypical characterization in situ

In the present study, we characterized intra-epithelial leukocytes in the digestive tract of chickens during postnatal development. Their phenotype was characterized by monoclonal antibodies in cryostat sections and the numbers of the different cell-types were counted in the epithelium of the esophagus, proventriculus, duodenum, jejunum, cecum, and colon. All intra-epithelial leukocytes bore the leukocyte-common antigen CD45; 35% were T lymphocytes, and 50% bore a B-cell marker. However, no immunoglobulin-bearing cells were detected in the epithelium. Monocytes and macrophages were found only in the epithelium of the esophagus. A remaining population of non-B, non-T, non-monocyte cells (15%) was present in all parts of the digestive tract. The number of intra-epithelial leukocytes was greatest in the duodenum and jejunum, and decreased in the proximal part of the cecum and in the colon. Intra-epithelial leukocytes were only sporadically detected in the proventriculus. The total number of intra-epithelial leukocytes increased until 8 weeks after hatching and then decreased at 18 months. In the esophagus, the total number of intra-epithelial leukocytes changed little during aging. We found that the intra-epithelial leukocytes of chickens and rodents are distinct in that chicken intra-epithelial leukocytes comprise a cell population that bears a B-cell antigen but that lacks surface immunoglobulins.

Cytotoxic potential of intraepithelial lymphocytes (IELs). Presence of TIA-1, the cytolytic granule-associated protein, in human IELs in normal and diseased intestine

Human intestinal intraepithelial lymphocytes (IELs) have phenotypic characteristics of cytotoxic T cells, yet a cytotoxic function has not been demonstrated in redirected lysis assays. A monoclonal antibody that reacts with a cytotoxic granule-associated protein, TIA-1, was used in this study to identify this protein in many, but not all, IELs of normal human proximal small intestine. Furthermore, in active celiac disease, in which the number of IELs is significantly increased, a corresponding increase in the number of TIA-1 cells was found. These results indicate that whereas cytotoxicity of human IELs has been difficult to demonstrate, they contain at least one of the proteins associated with cytotoxicity, and a failure to demonstrate this function may be related to the in vitro assay system used.

Epithelial cells bearing class II molecules stimulate allogeneic human colonic intraepithelial lymphocytes

HLA-DR+ gut epithelial cells may present antigen to intraepithelial lymphocytes (IEL). This study aimed to isolate an IEL population from the human colon to activate CD3 + IEL by a human colonic epithelial cell line (HT-29), bearing different concentrations of class II antigen (HLA-DR). IEL were isolated by a mechanical method from six patients with ulcerative colitis (UC) and from 14 control patients. IEL were cocultured with HT-29 which had been induced to express class II molecules by gamma-interferon (IFN-gamma) in a dose dependent manner. The phenotype and the subsequent expression of activation markers by the IEL were determined to two colour flow cytometry. The IEL population had a CD4/CD8 ratio similar to that seen in tissue sections. In the mixed cell culture, the degree of IEL activation showed a positive correlation with the degree of HLA-DR expression by the HT29 cells and the IEL secreted a IFN-gamma like factor that in turn stimulated the HT-29. Thus, depending on their expression of HLA molecules, colonic epithelial cells are able to activate CD3+CD8+IEL.

Whipple's disease: a histological, immunocytochemical and electronmicroscopic study of the immune response in the small intestinal mucosa

Whipple's disease is a multisystem disorder with protean manifestations and with poorly understood aetiopathogenesis. It is unclear how the immune system reacts, whether it functions normally or not, whether it protects the organism or is defeated in one way or another by the 'Whipple bacillus'. The purpose of our study was to assess humoral and cellular immunity at the level of the intestinal mucosa. This histochemical, immunocytochemical and electronmicroscopic study, based on 16 cases, has shown that the changes in components of the mucosal immune system in Whipple's disease are quite different from normal. The phagocytic capacity of the macrophages, assessed microscopically, is abnormal, the number of intra-epithelial lymphocytes is increased, the CD 4/CD 8 cell ratio is decreased and the IgM positive cells in the lamina propria outnumber the IgA positive cells. These changes may be inter-dependent.

Lymphocyte and macrophage subpopulations in pelvic ileal pouches

This study aimed to characterise the mucosal cellular infiltrate in ileal reservoirs with and without pouchitis (reservoir ileitis). Intraepithelial lymphocyte counts were performed in biopsy specimens obtained from ileal pouches and compared with counts in normal ileum and normal colon. T lymphocyte and macrophage subpopulations were characterised immunohistochemically in pouch biopsy specimens using a panel of monoclonal antibodies. Normal ileum was used as a control. Intraepithelial lymphocyte densities (expressed as intraepithelial lymphocyte/100 epithelial cells) in pouches with and without pouchitis were significantly less than in normal ileum, and approached counts found in normal colon. There was no significant increase in counts even in pouchitis. There were no significant differences in the helper/inducer to suppressor/cytotoxic T cell (CD4:CD8) ratios between normal ileum and pouches with or without pouchitis, either in the epithelium or in the lamina propria. The proportions of RFD9+ (epithelioid cells and tingible body macrophages) and 3G8+ (CD16) macrophages were significantly higher in pouchitis compared with pouches without pouchitis or normal ileum. There were no significant differences between the three groups in the proportions of cells positive for the other macrophage markers (CD68, RFD1-dendritic cells, and RFD7-mature macrophages). The significance of low intraepithelial lymphocyte counts in ileal pouches is unknown, but this may be an adaptive response to the new luminal environment. Since an increase in RFD9+ macrophages occurs in inflammatory bowel disease, but does not occur as a non-specific response to an acute infective process, their presence in pouchitis suggests that effector mechanisms similar to those triggering the original ulcerative colitis may be operating in pouchitis.

Pneumonitis in bone marrow transplant recipients results from a local immune response

Eighteen recipients of allogeneic T cell-depleted bone marrow who developed 22 episodes of interstitial pneumonitis were investigated by bronchoalveolar lavage for the cause of pneumonitis. The cells obtained were examined using a panel of monoclonal antibodies with immunocytochemical techniques to identify lymphocyte subsets and the presence of surface molecules indicative of lymphocyte activation. The majority of patients had an excess of lymphocytes in lavage and most of these cells were positively stained with the McAb recognizing the CD8 antigen (suppressor/cytotoxic type T cells). Although the proportions of CD4+ (helper type) T cells were below normal, the absolute numbers were within normal limits, thus the CD4:CD8 ratio was consistently 1:1 or less. A large proportion of the CD8+ cells displayed HLA-DR molecules (RFDR1+), interleukin-2 (IL-2) receptors (CD25+) and high concentration of CD7 antigen (RFT2+). Further analysis revealed that most CD8+ cells were CD5+ (RFT1+) yet a large proportion (20-40%) were CD5-. A majority of CD8+ cells was also CD38+ (RFT10+) and Leu7+. No clear correlation between the emergence of a raised proportion of activated CD8+ cells and diagnosed cytomegalovirus infection was found. These results demonstrate, however, that cells with the phenotype of the resident T cells of the bronchial epithelium (CD8+CD5-) emerge to the air spaces and express activation markers. This raises the intriguing paradox of an aggressive local immune response occurring in an otherwise immunosuppressed group of patients.

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.

Lymphocytic gastritis in patients with celiac sprue or spruelike intestinal disease

A distinctive form of gastritis, characterized by lymphocytic infiltration of pit epithelium, has recently been described in association with evidence of Campylobacter pylori infection. We have evaluated simultaneous small bowel and gastric biopsies from 22 patients with diarrhea or malabsorption, all of which showed small bowel changes characteristic of sprue or spruelike disease. In 10 of 22 patients, striking lymphocytic gastritis was identified. Cases positive for lymphocytic gastritis had a mean of 46.5 lymphocytes per 100 epithelial cells, compared with a mean of 3.5 in normal gastric controls and 5.1 in abnormal controls, including cases with Campylobacter gastritis. Concurrent small bowel biopsies had a mean of 47.2 lymphocytes per 100 epithelial cells. Cases without lymphocytic gastritis had means of 10.8 and 39.9 lymphocytes per 100 gastric and intestinal epithelial cells, respectively. Campylobacter organisms were identified in only 1 of the 10 patients with lymphocytic gastritis and in 3 of the 12 patients without lymphocytic gastritis. Intraepithelial lymphocytes in small bowel and stomach were positive for the antibody MT-1, indicating a T-cell infiltrate at both sites. These findings suggest that lymphocytic gastritis may occur as a manifestation of celiac sprue or spruelike disease and that the lymphocytic infiltration of celiac sprue may affect gastric epithelial mucous cells.

A rabbit model for mucosal immunity in the bowel. II. Local cellular reactivity to virus infection

An animal model was used to examine local and systemic cellular reactivity against virus infection of bowel mucosa. Firstly, existing techniques for extracting lymphoid cells from the dispersed populations of the bowel mucosa were adapted for use in rabbits and viable lymphocytes were isolated from the lapine ileal mucosa in numbers suitable for assay. Lamina propria lymphocytes (LPL) showed a strong blastogenic response to T-cell mitogens but intra-epithelial lymphocytes (IEL) responded poorly, even in the presence of splenic accessory cells. Next, chronically isolated ileal loops in rabbits were infected with parainfluenzavirus type 3 (PI-3) and isolates from the organized and dispersed lymphoid tissues associated with infected ileal mucosae and those from systemic lymphoid sites were used in in vitro assays of virus-specific lympho-proliferation. A T-cell-mediated immune response against PI-3 was mounted in lymphoid tissues associated with the infected loops, appearing first in loop Peyer's patches (PP) at Day 4 and in mesenteric lymph nodes (MLN) and lamina propriae at Day 7 after infection. The response in PP had waned by 21 days but was sustained in the other sites for at least 42 days. Epithelial lymphocytes were consistently anergic and there was no evidence of specific reactivity at systemic lymphoid sites or elsewhere in the bowel. Thus, a highly localized T-cell-mediated response was sustained, not only in organized lymphoid tissues but also in the bowel wall itself, following infection with a novel antigen.

Intraepithelial T cells of the TcR gamma/delta+ CD8- and V delta 1/J delta 1+ 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.