Immunological analysis of the rats with anterior hypothalamic lesions

We have previously identified the suppression of lymphocyte blastogenesis and the acceleration of growth of subcutaneous tumors by bilateral anterior hypothalamic lesions in rats. The present study was performed to clarify the changes in lymphocyte subsets and natural killer (NK) activity after making the lesions. The influence on immunological memory was also studied. The CD4/CD8 ratio of peripheral blood lymphocytes and spleen cells, T cell receptor alpha beta-positive cells of the thymocytes and NK activity of the spleen cells decreased significantly. Major histocompatibility complex (MHC) antigen expression on RBL-1 cells injected intraperitoneally into pre-immunized rats was also suppressed. These results suggest that the anterior hypothalamus has some influences on the control of the cellular immunological functions at the peripheral level, on the maturation of T cells at the level of thymus and on the antigen recognition by T cell receptors and MHC antigens.