Glutenin is involved in the gluten-driven mucosal T cell response.

Gluten ingestion causes coeliac disease in susceptible individuals. Gluten is a heterogeneous mixture of glutenin and gliadin, the latter of which is considered responsible for disease induction. By combining high-performance liquid chromatography purification steps of gluten with a T cell bioassay and mass spectral analyses, we have identified a glutenin peptide (glt04 707-742) that activates T cells from the small intestine of a coeliac disease patient and results in the secretion of large amounts of IFN-gamma. The minimal T cell stimulatory core of the peptide (residues 724-734) is repetitively present in glutenin molecules. Moreover, it was observed that a large number of naturally occurring variants of this peptide are recognized by the T cells. These data suggest that the large heterogeneity of glutenin proteins dramatically increases the number of available T cell epitopes. Together, the results provide new insight into the nature of the gluten antigens that lead to coeliac disease and suggest that glutenin, next to gliadin-derived antigens, may be involved in the disease process.

Small intestinal T cells of celiac disease patients recognize a natural pepsin fragment of gliadin.

Celiac disease is a common severe intestinal disease resulting from intolerance to dietary wheat gluten and related proteins. The large majority of patients expresses the HLA-DQ2 and/or DQ8 molecules, and gluten-specific HLA-DQ-restricted T cells have been found at the site of the lesion in the gut. The nature of peptides that are recognized by such T cells, however, has been unclear so far. We now report the identification of a gliadin-derived epitope that dominantly is recognized by intestinal gluten-specific HLA-DQ8-restricted T cells. The characterization of such epitopes is a key step toward the development of strategies to interfere in mechanisms involved in the pathogenesis of celiac disease.

Spondyloarthropathy and idiopathic inflammatory bowel diseases.

: Spondyloarthropathy (SpA) as observed in patients with idiopathic inflammatory bowel diseases is categorized according to the recently developed criteria of the European Spondylarthropathy Group, and belongs to a large complex of rheumatic disorders, encompassing ankylosing spondylitis, Reiter's disease, psoriatic arthritis, and reactive arthritis. It has been recognized for many years that patients with ulcerative colitis or Crohn's disease frequently have arthritic complications. The gastroenterologist should therefore carefully evaluate any symptom of peripheral or axial arthritis, in an attempt to provide an accurate diagnosis, to define a realistic prognosis, and to establish adequate therapy at an early stage. In this review, clinical and etiopathogenic aspects are analyzed, not only of patients with inflammatory bowel diseases and SpA, but also of patients developing arthritic symptoms after gastrointestinal bacterial infections (reactive arthritis). The significance of ileal mucosal inflammation as observed frequently in patients with SpA is discussed; the contribution of immunogenetic factors in the development of SpA, such as HLA-B27, is briefly reviewed. Finally, analysis is made of the different therapeutic options that are available at present.

Antireticulin antibodies in collagenous and lymphocytic (microscopic) colitis.

Serum antireticulin antibodies (ARAs) are often present in patients with dermatitis herpetiformis and celiac disease (CD), especially before instituting a gluten-free diet. In both collagenous colitis (CC) and lymphocytic (microscopic) colitis (LC) the colorectal mucosa shows surface epithelial damage with intraepithelial lymphocytes that is strikingly comparable to the small intestinal findings in CD. Also, CD may show subepithelial collagen deposition resembling that seen in CC. Because of these similarities, ARAs were measured in sera from patients with biopsy-proven CC and LC and compared with sera tested from CD patients. Antibody binding to reticulin was detected in frozen sections of rat liver and kidney by indirect immunofluorescent techniques. Whereas five of 14 CD patients (35.7%) had ARAs, only one of 29 CC patients (3.4%) (P = 0.010 versus CD) and none of 17 LC patients (0%) (P = 0.012 versus CD) had ARAs. The positive CC patient had IgA ARA titers of 1:20 noted in two sera taken 2 mo apart. The five positive CD patients had IgA ARA titers ranging from 1:20 to 1:320. The rare presence of ARAs noted in collagenous colitis and lymphocytic colitis was similar to its occurrence in normals, whereas the frequency of ARAs found in celiac disease (35.7%) was within the range reported for that disorder. Therefore, ARAs do not appear to be associated with CC or LC despite the morphologic similarities to CD.

Impaired local natural killer cell activity in human colorectal carcinomas.

The present study was undertaken to study natural killer (NK) cell activity in patients with colorectal cancer at peripheral and local levels. Mononuclear cells were isolated from uninvolved colorectal mucosa, tumor tissue and peripheral blood, and tested against the colon carcinoma cell line CaCo-2 and the erythroleukemia cell line K-562. Peripheral blood NK cell activity from the patients showed similar levels compared with healthy controls, whereas, mononuclear cells of tumor tissue were found to have a significantly decreased NK cell activity compared to the normal intestinal mucosa (P less than 0.01). No relation was found between the NK cell activity and the advancement of the disease according to the Duke's stage. Interferon-gamma (IFN-gamma) stimulated the NK cell activity of the mononuclear cells from blood, mucosa and tumor. However, the increase of NK cell activity after IFN-gamma stimulation was lower in the tumor compared to the mucosa (P less than 0.02). The lectin, phytohaemagglutinin, increased the cytotoxicity of mononuclear cells from blood, mucosa and tumor to a similar level. These results suggest that patients with colorectal tumors exhibit a normal NK cell activity in peripheral blood and intestinal mucosa; however, a diminished NK cell activity exists at the tumor level. Although mononuclear cells isolated from the tumor have a normal response to lectin stimulation they show hyporesponsiveness to IFN-gamma stimulation with regard to their NK cell activity.

The prognosis of ileorectal anastomosis in Crohn's disease.

A total of 105 patients have been treated with colectomy and ileorectal anastomosis from 1958 to 1978 in Birmingham, England (48) and in Leiden, Netherlands (57). At the end of 1978 the mean follow-up was 7.6 years (6 months-20 years). Mild or moderate degrees of proctitis were not considered as contraindications for ileorectal anastomosis. The presence or absence of ileal disease or perianal disease at the time of ileorectal anastomosis did not effect the long term prognosis but patients with sigmoidoscopic proctitis appeared to fare less well (69 per cent still functioning) than those with an apparently normal rectum (87 per cent). However, no statistical significance was obtained. The risk of reoperation for recurrence of Crohn's disease after ileorectal anastomosis calculated by actuarial methods shows a 50 per cent cumulative reoperation rate after 16-20 years. This result suggests that ileorectal anastomosis is a safe and useful procedure for most patients with Crohn's colitis who did not have severe proctitis.