Lymphocyte subsets in an experimental model of chronic pancreatitis in rats

The role of immunocompetent cells in chronic pancreatitis is poorly understood. Therefore, lymphocyte subsets were analyzed in pancreatic tissue, in peripheral blood, and in regional lymph nodes using an experimental chronic pancreatitis in rats. Methods: Pancreatitis was induced by intravenous application of dibutyltin dichloride (DBTC, 8mg/kg body weight). 5 rats per group were killed 1, 3, 5, 7, 14, 28, and 60 days after treatment. Pancreata were removed and examined immunohistochemicaUy with the APAAP technique. Peripheral blood and regional lymph nodes were obtained for isolation of lymphocytes followed by analysis of lymphocyte subsets using FACScan, Antibodies were directed to T lymphocytes, CD4+ helper T cells, CD8+ suppressor/cytotoxic T ceils, interleukin-2 receptor (CD25+), and B cells, Lymphocyte function was determined using the Concanavalin A (Con A) stimulated lymphocyte transformation assay with 3H-thymidine. Results: In DBTC-treated animals, we could demonstrate persistent infiltration of pancreatic tissue with lymphocytes. There was a predominance of CD4+ T cells compared to CD8+ T cells. However, CD8+ cells as well as CD25+ cells increased during the observation period. Number of B cells was low. During the observation period, no differences in the lymphocyte subsets in peripheral blood or in lymph nodes, were observed. Regarding lymphocyte function, we found significantly increased values of Con A induced lymphocyte transformation in regional lymph nodes in the course of pancreatitis. In peripheral blood, these changes could not be demonstrated. Conclusions: DBTC-pancreatitis was characterized by persistent infiltration of pancreatic tissue with CD4+ cells. CD8+ cells as well as activated lymphocytes increased. This indicates that suppressor/cytotoxic T cells play a role in the pathogenesis of experimental chronic pancreatitis. Regional lymph nodes were involved in the local inflammatory process. Supported by BMBF, FKZ 01/ZZ/9102