[Allotransplantation of isolated pancreatic islets in diabetic rats. Effect of culture on islet rejection].

Reduction of the immunogenicity of the tissue by tissue culture has been a controversial concept in transplantation immunology. In the present study, isolated islets were cultured prior to allotransplantation. The obtained results were compared in comparison with the results of the non-cultured islet allotransplantation group. Two kinds of rats differing from each other in histocompatibility antigen were used. WKA rats ( RT1k ) were donors, and LEJ rats ( RT1j ) recipients. No immunosuppressive agents were given. About 500 isolated islets of the donors were transplanted to the spleen of the recipients with streptozotocin induced diabetes mellitus. Although the mean survival time of non-cultured islet was 12.2 +/- 4.3 days, that of 7-day cultured islet increased significantly to 26.4 +/- 4.8 days. The response of the lymphocytes to the islets was also examined by mixed lymphocyte-islet culture. Response of lymphocytes to non-cultured islet was compared with that of lymphocytes to 7-day cultured islets. The response of lymphocytes to the 7-day cultured islets was significantly decreased. These results suggested that the cultured islet prolongs survival time and islet culture diminish the concentration or availability of stimulatory antigens on the cell surface membranes.