Isolation and characterization of a colonic autoantigen specifically recognized by colon tissue-bound immunoglobulin G from idiopathic ulcerative colitis

Autoantibodies to colonic cells and subcellular fractions in inflammatory bowel disease: do they exist?

Previous observations have purported to demonstrate circulating antibodies which bind to colon epithelial cells. However, the significance and reproducibility of such observations has been difficult and the data often phenomenological. To further our understanding of such autoreactivity, we studied sera and purified serum immunoglobulins from patients with ulcerative colitis, Crohn's colitis and other inflammatory diseases, as well as normal volunteers using as a target, well-defined epithelial cell preparations from normal and diseased colon and small bowel including crude suspensions of homogenized cells, purified and characterized brush border membranes, basolateral membranes and a DEAE cellulose column purified protein fraction. Homogenates of normal liver, lung, kidney, thymus, pancreas, stomach and small and large intestine, obtained at surgery, were also included. The purified preparations were characterized by enzyme activity and were electrophoresed on SDS-polyacrylamide gels for immunoblotting. Additional studies were carried out comparing these findings with those of a previously published and described 'positive' colon target preparation and polyclonal antibody. There was no convincing demonstration of circulating autoantibodies in patients with ulcerative colitis. Our data, using well-defined and characterized tissue preparations, raises doubts regarding the presumptive demonstration of autoantibodies in ulcerative colitis.

A shared and unique epitope(s) on human colon, skin, and biliary epithelium detected by a monoclonal antibody

An immune-complex-mediated inflammation has been suggested in the pathogenesis of skin and biliary complications in ulcerative colitis, although specific antigen-antibody complexes have not been found. We recently identified an Mr 40,000 colonic protein that reacts with tissue-bound immunoglobulin G eluted from colon specimens of patients with ulcerative colitis and not with immunoglobulin G eluted from colon specimens of patients with other diseases (J Clin Invest 1985;7:311). Murine monoclonal antibodies to the purified Mr 40,000 colonic protein are developed. The presence of the Mr 40,000 protein was examined with a monoclonal antibody (7E12H12, immunoglobulin M isotype) by an immunoperoxidase assay against various human epithelial tissues (74 specimens) including colon, ileum, jejunum, duodenum, stomach, esophagus, pancreaas, liver, respiratory, urinary, and genital tracts. In addition, gall bladder, bile duct, hepatic ducts, skin, synovial membrane, and eye tissue were also examined for any cross-reactivity with 7E12H12 and another anti-Mr 40,000 monoclonal antibody (7E6A5, immunoglobulin G1 isotype). 7E12H12 reacted only with colonic-epithelial cells mainly along the basolateral domains of plasma membrane and apical areas. The reactivity was present in both adult and fetal colon including the appendix. Among all the noncolonic tissue specimens, 7E12H12 reacted only with the gall bladder, the bile duct, the hepatic ducts, and the skin. All other epithelial tissues from 15 different organs, including the small intestine, synovium, and eye tissue, did not react. In the skin and biliary tract the immunoreactivity was exclusively present in the epidermal epithelial cells and mucosal epithelium respectively. 7E6A5 stained colonic mucosal cells but did not react with skin, biliary epithelium, synoyium and eye tissue. These results indicate the presence of a unique epitope or epitopes on Mr 40,000 colonic epithelial protein that is shared by the skin and biliary tract epithelial cells. Future studies of this shared epitope or epitopes and its immune recognition may provide further understanding in the pathogenesis of extraintestinal complications involving these organs in patients with ulcerative colitis.

Aetiology and pathophysiology of chronic liver disorders

The aetiology of chronic liver disease covers a wide range of congenital or acquired abnormalities of the hepatocellular biochemical network. Although our knowledge has considerably increased in recent years, the aetiology of chronic liver disease often remains obscure. Acquired irreversible disturbances of normal liver function can be mediated by hepatotrophic viruses, chemicals, chronic oxygen depletion, or interference with the immune system. Considerable progress has been made in the detection and characterisation of hepatitis B, C, and D viruses as causative agents of chronic active hepatitis. Alcohol abuse remains the predominant cause of chronic liver disease in the Western world. The targets of autoantibodies used to diagnose autoimmune diseases of the liver and primary biliary cirrhosis continue to be biochemically defined. Their significance for the aetiology of the disease, however, remains to be established. Nonparenchymal cells play an important role in the sequence of events following hepatocellular injury and ultimately leading to liver cirrhosis. They release vasoactive compounds, cytokines, and other important mediators, and participate in the modulation of the extracellular matrix that is characteristic of liver fibrosis and cirrhosis. The biochemical basis of liver cell necrosis remains poorly defined. In spite of recent progress, and the detection of some new pathogenic principles that help in the understanding of the complications of chronic liver disease such as portal hypertension, oesophagogastric variceal bleeding, portosystemic encephalopathy, ascites, and other metabolic disturbances, many questions concerning the aetiology and pathophysiology of chronic liver disease and its complications remain to be answered.

Immune events associated with inflammatory bowel disease

Immunologic abnormalities have been implicated in the etiology of inflammatory bowel disease (IBD). Defects of systemic immunity and of local (intestinal) immunity have been studied. The numbers of T and B lymphocytes and their characteristics seem to vary with the disease, but no cause-and-effect relationship has been established. The presence of anticolon antibodies in patients with ulcerative colitis suggests that these antibodies could be involved in IBD, but they have also been found in other conditions. In the peripheral blood, abnormalities of cell-mediated immunity are inconsistent and suggest that they are not fundamental defects of the disease. The hypothesis that the inflammatory process is a result of immune-mediated intestinal tissue damage is being extensively studied. The high familial incidence of the disease suggests a role of histocompatibility locus antigens, but no reproducible association can be established. In vivo and in vitro studies of mucosal mononuclear cells have revealed abnormalities of immunoglobulin production, some types of cytotoxicity against gut-derived antigens, and altered lymphokine production associated with the disease. Further studies of the intestinal immune system would seem to be the most fruitful line of research.

Possible role of vascular endothelial cells in immune responses in colonic mucosa examined immunocytochemically in subjects with and without ulcerative colitis

Phenotypic characteristics of vascular endothelial cells of the colonic mucosa in patients with ulcerative colitis and healthy controls were studied with immunoperoxidase staining by light and electron microscopy. The cells could be classified into two groups according to their phenotypes; one was positive for von Willebrand factor and the other had an antigen detected by a monoclonal antibody, OKM5. The endothelial cells positive for von Willebrand factor were usually in relatively large blood vessels, and OKM5-positive cells were mostly located in small capillaries along the glandular epithelium. OKM5-positive endothelial cells also expressed HLA-DR and interleukin-1 (IL-1). In patients with ulcerative colitis, OKM5-positive endothelial cells and spindle-shaped cells that might be precursors of endothelial cells were more numerous in the lamina propria than in the other subjects. Thus, OKM5-positive endothelial cells may be important as antigen-presenting cells and immunoregulatory cells in the intramucosal immune system. Furthermore, colonic epithelial cells in patients with ulcerative colitis synthesized HLA-DR and IL-1, and may have a close relation to immune responses, such as antigen processing and presentation to immunocompetent cells. It was suggested that these cells have a close relation to the pathogenesis of the impaired immune responses in situ in ulcerative colitis.

Period and generation effects on mortality from idiopathic inflammatory bowel disease

To test the hypothesis that environmental factors play a role in idiopathic inflammatory bowel disease (IBD), age, period, and generation (cohort) effects on IBD mortality in the United Kingdom and the United States were examined. The crude death rate of ulcerative colitis has declined since 1930. Plotted versus the year of birth, its age-specific death rates showed an initial rise in successive generations born between 1850 and 1900, followed by a fall in all later generations. The crude death rate of Crohn's disease increased from 1950 to 1974 and then declined. When the age-specific death rates for Crohn's disease and ulcerative colitis were superimposed, the mortality from Crohn's disease in each age group or sex began to decline at a different time, but always upon reaching the level of mortality from ulcerative colitis. It appears as if the gradual disappearance of an ulcerative colitis-associated factor in a birth-cohort fashion prevented a further rise in mortality from Crohn's disease after 1974.

Ulcerative colitis: specific antibodies against a colonic epithelial Mr 40,000 protein

A colon tissue-bound disease specific IgG (CCA-IgG) antibody can be eluted from the colonic tissue of patients with ulcerative colitis (UC). CCA-IgG recognizes an Mr 40,000 protein present in both normal and diseased colon. Using an anti-Mr 40,000 murine monoclonal antibody this protein has been localized exclusively in colonic epithelial cells mainly along the baso-lateral domains of plasma membrane. Non-colonic epithelial tissues from 12 different organs including small intestine did not react with the anti-Mr 40,000 monoclonal antibody. The Mr 40,000 protein is present in the RPMI-4788 colon cancer cells but not in HeLa. The antibody dependent cell-mediated cytolysis by UC sera against RPMI-4788 cells was inhibited by anti-Mr 40,000 polyclonal antibody. These findings suggest that CCA-IgG and the Mr 40,000 colonic epithelial protein are involved in an autoimmune reaction and may be important in the pathogenesis of UC.

Enhanced peripheral blood T-cell cytotoxicity in inflammatory bowel disease

Monoclonal antibodies to the CD3 component of the T-cell antigen receptor can trigger antigen-specific cytotoxic T cells to elicit nonantigen-specific cytotoxicity, possibly by mimicking or bypassing the requirement for antigen triggering. We have used this technique to investigate the possible presence of in vivo primed cytotoxic T cells, of unknown antigen specificity, in peripheral blood of patients with inflammatory bowel disease. Peripheral blood lymphocytes, which were depleted of background natural killer (NK) activity (CD16-), from patients with Crohn's disease exhibited significantly enhanced levels of anti-CD3-triggered T-cell cytotoxicity compared with lymphocytes from normal subjects. Enhanced lytic activity was also found in some patients with ulcerative colitis and in patients with ulcerative colitis postcolectomy. These results were not influenced by treatment or disease activity. There was no correlation between the anti-CD3-triggered T lytic activity and the NK activity in normal subjects or in patients with inflammatory bowel disease. The surface antigen phenotype of the anti-CD3-triggered T killer cell was CD3+, CD8+, CD16-, and Leu 7+. The results provide indirect evidence for increased activity of a subpopulation of cytotoxic T cells, of unknown antigen specificity, in inflammatory bowel disease. Increased activity in patients with ulcerative colitis postcolectomy suggests that this might reflect a fundamental immunological disturbance.

Ulcerative colitis specific cytotoxic IgG-autoantibodies against colonic epithelial cancer cells

Serum antibodies cytotoxic to the colon cancer cell line RPMI 4788 were studied in 42 patients with ulcerative colitis, 61 patients with Crohn's disease, 27 patients with other inflammatory diseases (disease-controls) and 22 healthy controls. Cytotoxicity of antibodies towards RPMI 4788 was studied by means of a chromium release assay using peripheral blood mononuclear leucocytes of healthy subjects as effector cells. Using a four hour antibody dependent cell mediated cytotoxicity assay sera from 29% of ulcerative colitis patients contained antibodies cytotoxic for the target, while only 3% of the Crohn's patients and 6% of the disease controls and non of the healthy controls were positive. When an 18 hour assay was applied, however, not only 40% of ulcerative colitis patients, but also 14% of Crohn's patients and 21% of disease controls were found positive. The reactive antibody in the four hour assay was mainly of the IgG class, which points at a classical antibody dependent cell mediated cytotoxicity mechanism. In the 18 hour cytotoxic assay IgG and particularly IgM antibodies were found to be reactive. This suggests that in the latter case other cellular cytotoxic mechanism might be involved. There was a significant inverse correlation between the appearance of the ulcerative colitis restricted IgG-anticolon epithelial cell antibodies (four hour assay) and the disease activity (p less than 0.01). Absorption studies showed that the reactive antigen is not specific for ulcerative colitis colonic tissue, but is similarly found in Crohn's bowel tissue, and to a lower extent in normal bowel, liver and kidney. The reactive antigen, however, could not be detected in brain and lymphoblastoid cells.

Immunoglobulin-containing cells in the colonic mucosa of rabbits with carrageenan-induced colitis

Immunohistochemical analysis of immunocompetent cells in the colonic mucosa was performed with carrageenan-induced experimental colitis in rabbits. Colitis was induced by seven months of oral administration of lambda-degraded carrageenan following immunization with the same substances containing Freund's complete adjuvant. In the colonic mucosa with colitis, IgG- and IgM-containing cells were significantly increased in number (IgG: 540 +/- 94/mm2 in experimental group, vs. 120 +/- 54/mm2 in control, P less than .05, IgM: 55.0 +/- 19.7/mm2 in experimental group, vs. 6.7 +/- 2.4/mm2 in control, P less than .05). There was no significant increase of IgA-containing cells either in number or in proportion to the total mononuclear cells. These changes, induced by carrageenan in rabbits, had resembled those in human ulcerative colitis well. These observations suggested an impairment of the IgA-regulated local immune system and an abnormality in the differentiation process of immunoglobulin-secreting cells.

Emergence of antigenic glycoprotein structures in ulcerative colitis detected through monoclonal antibodies

The emergence of new glycoprotein structures in colonic mucosa from patients with ulcerative colitis (UC) was assessed through the development of monoclonal antibodies (MAbs). Hybridomas were prepared from mice immunized with mucin glycoproteins purified from UC colonic tissue. Supernatants of 11 fusion products among 1200 fusion products that were screened in a solid-phase binding assay differentially bound UC-derived colonic mucin glycoproteins relative to comparable preparations from normal or Crohn's colitis tissue. These hybridomas were double-cloned to yield MAbs designated as MAbs UC 1-11. Disease-related specificity of MAbs UC 1-11 was determined through assessment of binding to beads coated with mucin glycoproteins purified from individual samples of UC tissue (n = 15), normal tissue (n = 21), and Crohn's colitis tissue (n = 10). Monoclonal antibody UC 7, an MAb of immunoglobulin G2A subclass, showed differential binding in solid-phase assays to UC mucin glycoproteins, with a mean binding of 10,170 +/- 2740 cm per UC glycoprotein-coated bead versus 2300 +/- 1080 and 2470 +/- 1525 cpm for normal and Crohn's colitis-derived glycoproteins, respectively. Monoclonal antibody UC 11 showed similar differential binding to UC mucin glycoproteins (9860 +/- 680 cpm vs. 1770 +/- 420 cpm). Binding specificity in solid-phase assay was mirrored by colonic mucosal staining patterns assessed by indirect immunofluorescent staining. Monoclonal antibody UC 7 specifically stained colonic mucosa from 8 of 10 patients with active UC, none of the samples from 8 normal controls, and none of the samples from 11 disease controls (six with Crohn's colitis, five with other inflammatory disorders). Specific staining was present on both the epithelial surface and on cells scattered within the lamina propria. Staining by MAb UC 7 was also observed in 3 of 4 samples of proximal uninvolved mucosa from patients with left-sided ulcerative colitis and in 3 of 5 samples from UC patients without acute disease activity.

Alterations in mucosal content of colonic glycoconjugates in inflammatory bowel disease defined by monoclonal antibodies

The presence of several glycoconjugates in colonic mucosa of patients with inflammatory bowel disease was assessed through indirect immunofluorescent staining using a collection of 23 monoclonal antibodies directed against human colonic mucin glycoproteins (anti-HCM MAbs). Intensity and distribution of staining by three anti-HCM MAbs were significantly altered in mucosa from patients with ulcerative colitis (UC) (n = 14) when compared with normal tissue (n = 15) and with tissue from patients with Crohn's disease as well as other inflammatory disorders (n = 15). Staining by anti-HCM MAb 17, which binds to colonic mucin glycoprotein species IV and V, was absent or diminished in 86% of samples from patients with active UC in contrast to 14% of normal and disease control specimens. Reduction in anti-HCM MAb 17 staining was less marked in mucosal biopsy specimens from patients with UC lacking acute inflammatory activity (n = 8). In contrast to the apparent loss of the MAb 17-defined epitopes, staining with anti-HCM MAbs 10 and 22 was enhanced in UC tissue compared with normal and disease controls. Increased staining with MAb 10 was present in 93% of samples from UC patients demonstrating active inflammation. Increased MAb 10 staining was not apparent in noninvolved mucosa from UC patients, indicating that increased expression of the specified epitope is related to the acute inflammatory process. In contrast, indirect immunofluorescent staining with MAb 22 was apparent in both involved (78%) and uninvolved (67%) UC mucosa in contrast to normal and disease controls (less than 12%). In addition, staining with several other anti-HCM MAbs (MAbs 3, 11, 15) was modestly and variably diminished (14%-28%) in UC, Crohn's disease, and other inflammatory disorders. These findings demonstrate the presence of alterations in mucosal content of specific glycoconjugate structures in association with UC. Inflammatory processes may also result in broad changes in glycoconjugate determinants generally.

Polyclonal nature of the intestinal mucosal lymphocyte populations in inflammatory bowel disease. A molecular genetic evaluation of the immunoglobulin and T-cell antigen receptors

To define the clonality of the intestinal lymphocytes involved in the immune response of inflammatory bowel disease, we performed a molecular genetic analysis of the arrangement of the immunoglobulin and antigen-specific T-cell receptor genes of isolated lamina propria lymphocytes derived from resected intestinal specimens of 12 patients with Crohn's disease, 5 patients with chronic ulcerative colitis, and 7 patients with other gastrointestinal diseases. The sensitivity of this technique is sufficient to detect a monoclonal population when there is as little as 1% clonal expansion in a mixed cell population. In all these groups of patients, deoxyribonucleic acid from the non-T cells demonstrated only a germ-line gene pattern, and no non-germ-line rearrangements of immunoglobulin genes as assessed by an immunoglobulin-joining heavy-chain gene probe. Deoxyribonucleic acid from the lamina propria T cells showed a rearrangement pattern of the antigen-specific T-cell receptor beta- and gamma-chain genes that is characteristic of polyclonal T cells as assessed by T-constant beta- and T-joining gamma-gene probes. These results indicate that the lamina propria non-T and T-lymphocyte populations in inflammatory bowel disease and controls are polyclonal.

Bacteroides vulgatus outer membrane antigens associated with carrageenan-induced colitis in guinea pigs

Previous experiments with the carrageenan model for ulcerative colitis demonstrated that the inflammatory response in guinea pigs can be enhanced by immunization with Bacteroides vulgatus and subsequent feeding of this organism to experimental animals. The studies reported here show that antigens extractable from the bacterial outer membrane by EDTA are responsible for this effect. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was used to analyze the outer membrane proteins from various strains as well as the lipopolysaccharides (LPS) extractable by the phenol-water method. Although the observed pattern of outer membrane proteins was complex, the strains could be divided into two electrophoretic types (phenons) on the basis of immunoblotting against a panel of antisera. Cross-absorbed antisera used in immunoblotting experiments identified four outer membrane proteins uniquely associated with the phenon capable of enhancing the colitis inflammatory response. These proteins had molecular weights of 100,000, 57,000, 34,000, and 21,000 when measured in 8% to 12% acrylamide gradient sodium dodecyl sulfate gels. Other antigens identified included at least one type of smooth LPS, three types of rough LPS, and a common antigen of 30,000 molecular weight among the strains of B. vulgatus tested. The outer membrane preparations were used in animal immunization and challenge experiments, and the severity of colitis was correlated with one electrophoresis type. The potential role of membrane proteins in the enhancement of colitis is discussed.

Ulcerative colitis--a disease characterised by the abnormal colonic epithelial cell?

The leakiness of the cell membranes of colonic epithelial cells isolated by the collagenase/Dispase technique from normal or diseased colons was assessed in a 4 h 51Cr release assay. Cells from normal, adenoma bearing or cancer bearing colons showed 51Cr release of 8% or less in almost all of 46 cell populations tested. In contrast, cells from mucosa affected by ulcerative colitis [11.9 (4.3%) n = 23] or Crohn's disease [8.4 (2.7%) n = 18] released significantly more 51Cr than the non-inflamed groups. Values are expressed as mean (SD). Overall, release values were greater in ulcerative colitis than Crohn's disease (p less than 0.01). In Crohn's disease, cells obtained from histologically inflamed mucosa released significantly more 51Cr [9.7 (2.5%) n = 11] than those from non-inflamed mucosa [6.4 (1.5%) n = 7, p less than 0.02] whereas, in ulcerative colitis, abnormal release values were found in 8 of 13 cell populations isolated from mucosa showing no histological evidence of active disease. In five patients with distal ulcerative colitis, cells from mucosa not apparently involved demonstrated normal 51Cr release in four of five studies despite abnormal release from cells from involved mucosa suggesting that a diffuse abnormality of the colonic epithelial cell is not usually present. These data indicate that chronic mucosal inflammation per se is associated with abnormalities of the colonic epithelial cell but that, in ulcerative colitis, the abnormality remains in many patients with quiescent disease. Identification of the local factors responsible for such an abnormality may contribute to an understanding of the pathogenesis of ulcerative colitis.

Mucosal subclass distribution of immunoglobulin G-producing cells is different in ulcerative colitis and Crohn's disease of the colon

As a marked local immunoglobulin G (IgG) response has previously been found to be the most prominent immunopathological feature of both ulcerative colitis and Crohn's disease, the subclass distribution of colonic IgG-producing immunocytes was examined. This study included tissue specimens from 10 patients with ulcerative colitis and 8 with Crohn's colitis. Paired immunofluorescence staining was performed with subclass-specific murine monoclonal antibodies combined with a rabbit antibody reagent of IgG; the proportion of cells belonging to each subclass could thereby be determined in relation to the total number of mucosal IgG immunocytes. A significantly higher median proportion of IgG1 immunocytes was found in ulcerative colitis (81.3%) than in Crohn's colitis (66.5%). Conversely, the median proportion of IgG2 immunocytes was significantly higher in Crohn's colitis (24.9%) than in ulcerative colitis (9.4%). This disparity in the local IgG subclass response might reflect dissimilar mucosal exposure to mitogenetic or antigenic stimuli or genetically determined immunoregulatory differences in the two categories of patients.

Development of a monoclonal antibody specifically reactive to gastrointestinal goblet cells

A mouse monoclonal antibody (7E6A5) of IgG isotype, reacting specifically with mucin-producing goblet cells of the human gastrointestinal tract, has been developed. 7E6A5 reacts by an ELISA with colonic protein eluted from a DEAE column. A screening by immunoperoxidase assay of 76 specimens from 19 different human tissues showed that the immunoreactivity of 7E6A5 was confined exclusively in the globules of goblet cells in the colon, the appendix, and the small intestine. Nongoblet small and large intestinal epithelial cells did not react. Immunoelectron microscopy demonstrated the reactivity with mucin droplets in a homogeneous granular pattern inside the globules of goblet cells. Mucus-secreting cells from remaining parts of the gastrointestinal tract and other mucus-secreting organs such as respiratory, genitourinary tracts, salivary and mammary glands did not show any reactivity to 7E6A5. These findings indicate that the antigen recognized by 7E6A5 is shared by the goblet cells of both the small and large intestines and is unique to them. The monoclonal antibody may be useful in the study of function of mucus-secreting goblet cells and may represent an important tool in the evaluation of diseases such as ulcerative colitis, colon cancer, and intestinal metaplasia in gastric mucosa that are associated with quantitative changes in goblet cell numbers or with qualitative differences in mucin secretion.

Immune sensitization to syngeneic organ-specific intestinal antigens in the Lewis rat

In human chronic inflammatory bowel disease involving mucosal epithelium, sera and lamina propria mononuclear cells are reactive with cell surface components isolated from gut epithelial cells. To define a model system in which the disease-inducing potential of such immune factors could be rigorously evaluated, we sought to immunologically sensitize inbred murine strains to syngeneic colonic epithelial cell-associated components (ECAC-C), to define precise in vivo and in vitro conditions to optimize ECAC-C reactivity, and to initially explore whether such cells could elicit tissue injury in epithelium after adoptive transfer to naive animals. Following footpad immunization, Day 42 lymph node cells but not splenocytes were reactive with syngeneic ECAC-C, as shown by a linear increase in [3H]thymidine incorporation over a wide range of antigen concentration (0.5 to 100 micrograms/ml). A subsequent 48-hr exposure to ECAC-C and/or interleukin 2 resulted in a more restricted responsiveness, proliferation occurring only in the presence of ECAC-C or mitogen and not to a coimmunogen (PPD). Further evidence that lymph node cells from ECAC-C/CFA immunized animals were indeed sensitized to syngeneic ECAC-C included ability of donor animals to mount highly significant earlobe DTH responses to ECAC-C, indicating the presence of antigen-specific T-DTH cells, and the failure of polymyxin B, in doses sufficient to inhibit LPS-induced mitogenesis, to reduce lymph node cell responsiveness to ECAC-C, known to be contaminated with LPS. ECAC-C-specific circulating antibody and T-cytotoxic cells were not detected. Adoptive transfer of Day 42 lymph node cells, sensitized in vivo and conditioned in vitro, was not associated with tissue injury in syngeneic recipients in preliminary experiments. This model system, with antigen-specific cells analogous to those present in diseased mucosa of human chronic inflammatory bowel disease, may be an important means to determine the pathophysiologic significance of anti-epithelial cell immune responses in these disorders.