Effects of levamisole on the proliferation of thymic lymphocyte subpopulations

The ability of levamisole to enhance proliferation of murine lymphocyte preparations stimulated by concanavalin A was examined. Levamisole substantially augmented the proliferation of C57Bl/6 thymic lymphocytes, but had only marginal effects on the proliferation of splenic lymphocytes. The possibility that this difference was related to the degree of cell maturation was examined by peanut agglutinin fractionation of the thymic lymphocytes. Levamisole was found to stimulate proliferation most effectively in the mature fraction. However, since the focus of levamisole activity might be on macrophages, also shown to be present in preparations of splenic and thymic lymphocytes and in both PNA separated fractions, the drug's activity was compared to several macrophage replacements: LAF-IL 1, 2-mercaptoethanol, and added splenic adherent cells. Added plastic adherent cells and 2-mercaptoethanol were effective in augmentation of proliferation of both mature and immature populations whereas LAF-IL 1 like levamisole was most effective on the mature population.