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BACKGROUND/AIMS: A strong association exists between ulcerative colitis and primary sclerosing cholangitis (PSC). Previously, the presence of a unique epitope shared by colon and biliary epithelial cells was shown by using the novel monoclonal antibody (MAb) 7E12H12 developed against a colonic epithelial protein. In the present study, the presence of circulating autoantibody in PSC against this peptide was examined. METHODS: Sera from 16 patients with PSC, 13 with primary biliary cirrhosis, 6 with secondary biliary stricture, and 6 with chronic liver diseases and 10 normal subjects were used. An inhibition immunoperoxidase assay using the 7E12H12 MAb was developed against sections of bile duct and gallbladder. Sera were also examined in an enzyme-linked immunosorbent assay (ELISA) against the gallbladder extract enriched in 7E12H12-reactive protein. RESULTS: About two thirds of the sera from patients with PSC blocked the binding of 7E12H12 MAb on the bile duct and gallbladder, whereas non-PSC sera did not. In the ELISA, 93% of PSC sera had circulating immunoglobulin G antibodies against the enriched gallbladder extract. The reactivity of sera from the PSC group was significantly (P < 0.01 to P < 0.0001) higher than in each of the non-PSC groups. CONCLUSIONS: Sera from patients with PSC contains autoantibodies against a cross-reactive peptide shared by colon and biliary epithelial cells.

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Inflammatory bowel disease, in particular ulcerative colitis, is characterized by localization of leukocytes in close proximity to the colonic epithelium, which may be mediated by the expression of intercellular adhesion molecules (ICAM-1; CD 54). We previously reported the presence of an organ-specific M(r) 40K colonic protein that acts as an autoantigen in ulcerative colitis and is present on the surface of colonic epithelial cells and also in DLD-1 colon cancer cells. Using the colon tumor cell line DLD-1 and flow cytometry, ICAM-1 antibody binding by untreated cultured DLD-1 cells was similar to background antibody binding (mean channel number, MCN = 9.77 +/- 2.13). Interferon-gamma (100 U) induced a 1-2 log increase in anti-ICAM-1 antibody binding from as early as 12 hr after exposure up to 72 hr and a moderate increase (up to about 100%) in the binding of anti-M(r) 40K antibody. Additional studies showed that anti-ICAM-1 and anti-M(r) 40K antibodies bound to DLD-1 cells regardless of the presence of the other antibody. Taken together, the present observations suggest that the epitopes of ICAM-1 and M(r) 40K molecules are coexpressed by colonic epithelial cells, regardless of the presence of the other molecule. Furthermore, lymphocytes in the colonic mucosa that are activated to produce interferon-gamma may upregulate the expression of both of these molecules.

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The tissue distribution of a previously identified M(r) 40 K epithelial autoantigen in ulcerative colitis was examined in situ in the fetal tissue by immunocytochemical method, using an immunoglobulin M (IgM) monoclonal antibody (7E12H12). Fetal-autopsy tissue from 9 to 19 weeks of development (11-21 gestational weeks) gestations, including specimens of colon (20 specimens), skin (19), small intestine (12), gallbladder (15), liver (20), spleen (20), kidney (3), urinary bladder (3), and umbilical cord/placenta (25) were examined. 7E12H12 reactive epitope appeared first in a few colonic epithelial cells at 10 weeks of gestation. By 11 weeks, 7E12H12 reactivity was clearly evident in most of the colonic epithelial cells. Goblet-cell reactivity was evident from 15 weeks of gestation. Enterocytes lining the small intestine from all the specimens were negative. In the skin, earliest immunoreactivity was evident in the basal layer of epidermis at 10 weeks of development, and by 11 weeks, the staining was intense and localized exclusively to squamous epithelial cells of the epidermis. The immunoreactivity in the fetal gallbladder mucosa was also evident earliest at 11 weeks of development. The staining was distinct in the mucosal epithelial cells, and localized along the periphery of the cells and in the apical areas. None of the other tissue specimens reacted with 7E12H12. These results demonstrate that the 7E12H12 reactive epitope is novel, is shared by colon, skin, and biliary epithelium, and appears more or less simultaneously in the three organs at 10 to 11 weeks of development of the fetus. A possible link of this crossreactive protein or proteins in the immunopathogenesis of ulcerative colitis, sclerosing cholangitis, and pyoderma gangrenosum is discussed.

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We recently reported the presence of an organ-specific 40 kD colonic protein which acts as an autoantigen(s) in patients with ulcerative colitis. Using a specific monoclonal antibody directed against 40 kD protein (7E12H12, IgM isotype), in conjunction with immunocytochemistry and flow cytometry, we examined the presence of the 40 kD protein on human colon cancer cells, DLD-1, and also characterized the ability of cytokines, IFN-gamma and tumour necrosis factor, to modulate the expression of this protein on these tumour cells. The presence of the 40 kD protein was localized to the plasma membrane; less was present within the cytoplasm. Following exposure to IFN-gamma (10-1000 U/ml), DLD-1 colon tumour cells showed a dose- and time-dependent increase in 7E12H12 antibody associated immunofluorescence, with the maximum 7E12H12 antibody binding observed with 100 U/ml IFN-gamma at 48 h. In contrast, tumour necrosis factor did not alter the levels of anti-40 kD antibody binding over that of control cells. Since IFN-gamma is also known to induce class II major histocompatibility antigens, we examined the possibility of cross-reactivity of HLA class II antigens and Mr 40 kD epitope. Neither pre-incubation of DLD-1 colon tumour cells with anti-HLA class II antibodies followed by 7E12H12 nor co-incubation of both antibodies altered the amount of 7E12H12 antibody binding. Using a direct ELISA, a highly enriched preparation of Mr 40 kD protein reactive to anti-40 kD antibody did not react with HLA class II antibodies. The present results suggest that 40 kD protein is present on DLD-1 human colon tumour cells and that although the 40 kD protein epitope expression is increased by the lymphocyte-derived cytokine, IFN-gamma, the epitope is separate and distinct from the class II HLA antigens. Further studies on the 40 KD protein may elucidate its autoantigenic role in the pathogenesis of inflammatory bowel disease.

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Saguinus oedipus, Callithrix jacchus, and Saguinus fuscicollis are three species of New World monkeys which develop a form of colitis that is similar to human ulcerative colitis. Only S oedipus, however, develop colon cancer. We examined intestinal tissues from these animals for the presence of an antigen cross reacting to the Mr 40,000 human colonic epithelial protein that acts as an autoantigen in ulcerative colitis. Using an anti-Mr 40,000 monoclonal antibody (7E12H12, IgM isotype), by an immunoperoxidase assay we showed that all colon specimens from S oedipus reacted with 7E12H12; however, the colonic tissue from C jacchus and S fuscicollis did not. In immunotransblot analysis eluted IgG antibody bound to human ulcerative colitis colon (CCA-IgG) reacted with Mr 40,000 protein(s) present in the extracts of colon from S oedipus animals and humans. Small intestinal tissue reacted neither with 7E12H12 nor with CCA-IgG. In S oedipus, the Mr 40,000 protein was localised exclusively to colonic epithelial cells. Preincubation of seven S oedipus colon specimens with eight of 10 sera from animals with acute or chronic colitis and 0 of four sera from animals without colitis almost completely inhibited the binding of 7E12H12 to the colonic epithelium. Four of these 10 sera inhibited the binding of 7E12H12 to the autologous colon. These results show the presence of circulating autoantibodies in S oedipus with colitis against an epitope(s) on Mr 40,000 protein shared by human and S oedipus colon.

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Since its introduction, prenatal diagnosis of chromosomal and metabolic disorder by midtrimester amniocentesis has relied upon the use of a mixture of fetal cells obtained from amniotic fluid. Little knowledge has been gained in the sorting of these cells for diagnosis of tissue-specific disorders. In an attempt to determine the contribution of fetal colonic mucosal cells to the overall amniocyte population, we used the colonic epithelial-specific monoclonal antibody (MC-Ab) 7E12H12, IgM isotype. Specimens of the small intestine, colon, buccal mucosa, kidney, urinary bladder, and umbilical cord were obtained from electively aborted normal fetuses of 12-28 weeks' gestation. All of these specimens were examined with 7E12H12 by the immunoperoxidase technique. The MC-Ab reacted with the colonic epithelial cells but not with any of the other tissues. In addition, 40 amniotic fluid samples obtained from women between 16 and 18 weeks of gestation, who underwent amniocentesis because of advanced maternal age, were tested using a fluorescent activated cell sorter. Among the amniotic fluid specimens examined, 18.4 +/- 10.3 per cent cells reacted with 7E12H12. Double immunofluorescence studies revealed that all Mc-Ab-stained cells contained secretory component, confirming that they were epithelial in origin. All fetuses whose amniotic fluid was analysed had normal karyotypes and amniotic fluid alpha-fetoprotein levels that were also normal. This study demonstrates that cell-specific Mc-Ab can be used to detect colon cells in the amniotic fluid and that colon cells contribute significant numbers in the mixture of amniotic fluid cells.(ABSTRACT TRUNCATED AT 250 WORDS)

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