• DIFFERENTIAL BINDING OF GLUTEN PEPTIDES TO HLA CLASS II MOLECULES (DQ2) CORRELATES WITH IN VITRO AND IN VIVO TOXICITY IN COELIAC DISEASE. RG Shidrawi, S Rosen-Bronson*, A Wagner*, PJ Cielitira. Gastroenterology Unit, U.M.D.S., St. Thomas' Hospital, London, UK and *Georgetown University Medical Center, Washington, D.C. Coeliac disease is a gluten-sensitive enteropathy characterised by villous atrophy, crypt cell hyperplasia and lymphocytic infiltration of the lamina propria with CD4+ve T cells. The pathogenesis of this condition is thought to be a cell-mediated, class II-restricted process with antigen presentation occurring in the lamina propria. Immunogenetic studies suggest a tight HLA association between coeliac disease and HLA DQ2 (al*0501, 1310201). Recent work has demonstrated both in vitro and in vivo coeliac of a 19-met oligopeptide (peptide A) corresponding to amino acids 31-49 of Agliadin (Shidrawi, et al. Scand J Gastroenterol, in press, and Smrgess, et al. Lancet 1994; 343:758). Peptide B (amino acids 202-220 of Agliadin) includes a sequence homologous with the adenovirus 12 Elb sequence. Peptide C (amino acids 3-21 of A-gliadin) has PSQQ and QQQP tetra-peptide motifs and p-reverse turns, both implicated in toxicity. Neither peptide B nor peptide C induced toxic histological changes. Aim & Methods: To compare the relative binding of these glutenderived peptides to HLA class II molecules, we used lymphoblastoid Bcell lines derived from the peripheral blood of a patient with coeliac disease homozygous for HLA DQ2 in a competitive inhibition assay using an avidin/anti-avidin/avidin amplification technique to detect binding of a biotinylated indicator peptide (peptide MB) derived from a 65kDa Mycobacteriumbovis heat-shock protein and shown to bind selectively to affinity-purified HLA DQ2 (Johansen, et al. lnt Immunol 1994; 6:453). Results: A 20-fold signal:noise ratio was achieved in our flow eytometric assay using a final concentration of 250 mM of peptide MB. Significant inhibition of binding was observed with Frazer's Fraction III, a peptic:tryptic digest of gluten with known coeliac toxicity (76% inhibition at a 1:1 molar ratio), and peptide A (78% inhibition at a 5:1 molar ratio), but not with peptides B, C or ovalbumin over the same range of molar ratios. Conclusions: These findings support the hypothesis that peptide binding to HLA class II molecules (DQ2) and subsequent CD4+ve T cell activation is important in initiating the coeliac lesion and provide a new technique to dissect the molecular pathogenesis of coeliac disease. EXCESSIVE GLUTAMINE DETERIORATED ULCER HEALING IN A RAT COLITIS MODEL. M. Shinozaki, H. Saito, T. Sawada, Y. Saito, T. Muto. Dept. of Surgery, University of Tokyo, Tokyo, Japan [Background] Although the pathogenesis of Crohn's disease still remains unclear, elemental diet(ED ) is clinically effective in management. Glutamine is one of energy sources of many tissues including colonocyte. The aim of this study was to compare colitis by changing the quantity of glutamine in diet. [Methods]Colitis was induced by intrarectal administration of 30 mg trinitmbenzenesulfonic acid with 50% ethanol vehicle in Sprague-Dawley rats. Rats were randomly allocated to 3 groups: (group 1) commercially available ED (Elental) based diet with-out glutamine; (group 2) Elental; (group 3) Elental based ED with 24% glutamine. Diets were given from 1week prior to the induction of colitis until sacrifice. Rats were sacrificed at 1, 3, and 5 weeks after induction of colitis and colon was excised: Damage was evaluated by percent-age of rats with ulcer and average of ulcer area. [Result] (see table) At 1 week after induction, all groups were almost equally damaged. At 3 weeks, the averages of ulcer area in group 1 and 2 were equal, but a little higher in :group 3. At 5 weeks, ulcers almost diminished in group 1 and 2 , while there remained relatively larger ulcers in group 3. [Conclusion] It was suggested excessive glutamine deteriorated ulcer healing in trinitrobenzenesulfonic acid induced colitis. Time after induction