Prolongation of heart graft survival and spleen suppressor cell activity after donor specific blood transfusions in rats differing across the MHC.

The aim of the study was the prolongation of heart allograft survival in rats after DST (donor specific blood transfusion), the characterization of T and B lymphocyte phenotypes in peripheral blood, spleen and lymph nodes and the evaluation of specific and nonspecific suppressor cell activity of spleen and blood lymphocytes of DST rats. Pretreatment of Wistar recipients with one, two and three doses of DST-s prolonged the heterotopic August graft survival to 11.0, 12.3 and 11.4 days, respectively (rats differed across the MHC). Spleen lymphocytes of transfused rats showed significant nonspecific suppressive activity in culture with syngeneic spleen lymphocytes of nontransfused rats stimulated with PHA, but not in culture with blood lymphocytes. Blood lymphocytes of transfused rats did not show any nonspecific suppressive activity. Spleen and blood lymphocytes of transfused rats did not demonstrate any specific suppressive activity in allogeneic MLC. The ratio of W3/25+/OX8+ (Th+/Tsup/cyt+) cells in peripheral blood was found increased in DST rats due to the decrease in the percentage of OX8+ cells whereas the opposite effect was observed with spleen cells (increase in the percentage of OX8+ cells after one DST). The number of OX6+ (Ia positive) cells and B cells in all transfused rats was found unchanged comparing with untreated animals.