T cell-dependent class II major histocompatibility complex antigen expression in vivo induced by the diabetogen streptozotocin.

Immune reactions are involved in the low-dose streptozotocin (STZ)-model of hyperglycemia (1). By means of the popliteal lymph node assay, we demonstrated that T cell-dependent lymphoproliferation can be evoked by STZ (2). The present report shows that class II MHC antigen expression is readily inducible in multiple organs by a single dose of STZ injected subcutaneously (s.c.) into BALB/cJ mice. An increment of class II-positive cells of the lymphocyte and monocyte/macrophage lineage is discernible in the endocrine pancreas, kidney, and liver, but not the brain. In addition, renal tubular and bile duct epithelium express strong class II positivity. Class II antigens are not visible on pancreatic endocrine cells and hepatocytes. These immune phenomena are T cell-dependent, as assessed in tissues from BALB/cJ nu/nu recipients and their +/nu counterparts. STZ-induced class II antigens develop transiently and are not necessarily associated with organ dysfunction. The present STZ-induced MHC class II antigen aberrancies are in agreement with observations described recently by COCKFIELD et al. (3). In addition, we found that injection of methylnitrosourea, the aglycone of STZ, also resulted in class II MHC molecule induction in the liver, whereas the diabetogen alloxan failed to exert any effect on class II antigens.