Immunologic features of mice with streptozotocin-induced diabetes: depression of their immune responses to sheep red blood cells.

The immune responsiveness in streptozotocin (SZ)-induced diabetic mice was studied using the immune responses to sheep red blood cells (SRBC) as an indicator system. In SZ-diabetic mice, the weights of such lymphoid organs as the thymus and spleen were significantly decreased with time after SZ administration, whereas the weight of liver was markedly increased. In SZ-diabetic mice, the level of delayed type hypersensitivity (DTH) to SRBC was not lower than that in normal controls in most cases, although the level of DTH was significantly depressed, on occasion, in SZ-diabetic mice. In contrast, antibody-forming activity, measured as the number of plaque-forming cells (PFC), was markedly decreased in SZ-diabetic mice. It seems that antibody production is more profoundly depressed than is DTH in SZ-diabetic mice. The transfer of normal thymus and bone marrow cells into SZ-diabetic mice caused only a partial restoration of PFC activity. When normal spleen cells were transferred into diabetic irradiated mice, proliferation of spleen cells and production of splenic PFC was greatly reduced as compared with normal irradiated mice. Treatment with insulin completely reversed such depression in the transfer system. These findings suggest that the chronic insulin-deficient diabetic state caused a depression and delay in the proliferation and differentiation of lymphoid cells.