Effect of gamma-interferon on binding of gliadin and other food peptides to the human intestinal cell line HT-29.

gamma-Interferon is one of the main cytokines released during activation of intestinal lymphocytes in coeliac patients. The question has never been addressed whether gamma-interferon influences binding of gliadin and other food peptides to human enterocytes. Therefore, the human intestinal epithelial cell line HT-29 was cultured with gliadin, casein, beta-lactoglobulin and ovalbumin, with or without gamma-interferon, and peptide binding to cells was determined by flow cytometry and fluorescence microscopy. gamma-Interferon stimulated gliadin binding by a factor of 4. Binding was saturable with half maximal binding at 0.15 mg/ml. For maximal binding, an incubation of at least 24 h was necessary. gamma-Interferon increased binding of beta-lactoglobulin and casein, too, but inhibited that of ovalbumin. Binding of gliadin was inhibited by the other peptides. Under the conditions of ongoing mucosal inflammatory reactions and release of gamma-interferon, enhanced binding may trigger intestinal lymphocytes, increase secretion of cytokines and thus induce a vicious circle.

Effect of gliadin and other food peptides on expression of MHC class II molecules by HT-29 cells.

Expression of major histocompatibility (MHC) class II molecules by enterocytes is known to be enhanced in coeliac disease and other disorders characterised by intestinal inflammation--an effect thought to be mediated via intestinal lymphocytes. To investigate if food peptides can exert direct effects on class II expression, the influence of gliadins, casein, and beta lactoglobulin on an intestinal epithelial cell line (HT-29) was examined in the absence of immune cells. Class II expression was determined by flow cytometry and immunofluorescence microscopy using antibodies against the beta chain of all products of the gene subregions DR, DQ, and DP. MHC expression was low in HT-29 cells but could be stimulated by interferon gamma. Tryptin digested gliadin had no effect on class II expression. In the presence of interferon gamma, however, it was able to amplify MHC class II expression to mean (SEM) 150 (4)%. Casein exerted a similar effect (160 (14)%), but undigested gliadin, tryptin digested casein, and beta lactoglobulin had no influence. The observations suggest that within the concert of cytokine mediated interactions between enterocytes and lymphocytes, some dietary peptides could upregulate the presentation of food antigens, leading to a more efficient stimulation of lymphocytes, which in the case of coeliac disease might result in damage to the enterocytes.

Alzheimer's disease: a monoclonal antibody raised against paired helical filaments.

Paired helical filaments (PHF) were isolated from the cerebral cortex of patients with Alzheimer's disease (AD) by a combination of SDS treatment and density gradient centrifugation according to the method of Ihara et al. (1983). The protein component of the preparation was extracted with formic acid and Balb/c mice were used for immunization. Hybridoma supernatants were screened by immunocytochemical staining, by an ELISA assay, and by immunoblotting of SDS-PAGE, the latter both using the PHF preparation as antigen. One hybridoma which showed a strong reactivity with PHF in both the ELISA assay and immunocytochemistry was then used to produce ascites fluid in Balb/c mice. Antibodies reacted immunocytochemically with neurofibrillary tangles and neurites involved in plaque formation in AD but did not show a cross-reaction to human control brain and rat brain. The results indicate that the antibody which has been raised reacts with an antigen component of PHF.

[Experiences with the macrophage adherence inhibition test within the framework of preparing tumor-associated antigens from human breast cancers]. / Erfahrungen mit dem Makrophagenadhärenzhemmtest im Rahmen der Präparation von tumorassoziierten Antigenen menschlicher Mammakarzinome.

We try to prepare tumor-associated antigens from human mammary carcinomas by the use of several biochemical methods and to detect the biologic activity of these antigens with the macrophage adherence inhibition assay. The diagnostic relevance of the macrophage adherence inhibition assay was to improve by optimal enrichment of the tumor-associated antigens. By the use of this test system an enrichment of tumor-associated antigens was not detectable. Our results show, that the macrophage adherence inhibition assay because of its low sensitivity (53%) and the insufficient reproducibility can not be used as test system for tumor immunity in human cancer.

[Immunologic studies in patients with Crohn disease and ulcerative colitis]. / Immunologische Untersuchungen an Patienten mit Morbus Crohn und Colitis ulcerosa.

To compare patients with Crohn's disease and patients with ulcerative colitis we have studied some immunological parameters (level of IgM, IgG and IgA in the serum, number of lymphocytes, E rosettes) and the immunological reactivity to antigens from colon carcinoma and to colon antigens prepared from healthy and from colon tissue altered by Crohn's disease (antigen specific rosette test, MEM-test, antibody titer). The results indicate a decreased proportion of T cells in both bowel diseases on the one hand, on the other hand a specific cell-meditated immune reaction to colon antigens could be observed in patients with Crohn's disease. In patients with ulcerative colitis such reactions are determined only in the acute phase of disease or in recidive. It remains to be elucidated whether these immunological reactions represent a basic pathogenetic factor in the onset of these diseases.