Hypothalamic-immune interactions. II. The effect of hypothalamic lesions on the ability of adherent spleen cells to limit lymphocyte blastogenesis.

Animals with electrolytic pre-optic and anterior hypothalamic (AHT) lesions show impaired mitogen-induced lymphocyte blastogenesis which is restored by removal of a population of spleen cells with macrophage-like properties. Although suppressor macrophages are detectable in normal and control rats, substantially more activity is present following AHT destruction. Abrogation of lymphocyte activation does not result from increased numbers of splenic macrophages. These data indicate that one mechanism by which neuroimmunomodulation occurs is by induction of a qualitative alteration in the function of naturally occurring suppressor macrophages.