Deficiency in the incorporation of labeled thymidine and inhibition in the biosynthesis of interleukin-2 in lymphocytes obtained from Histoplasma capsulatum infected mice

The incorporation of (³H) thymidine and the biosynthesis of interleukin-2(IL-2) were investigated in Concanavalin A (ConA) and histoplasmin stimulated lymphocytes from spleen of infected Balb/c mice with the yeast phases of Histoplasma capsulatum. The ability to incorporate (³H) thymidine of Con A stimulated lymphocytes in culture from spleen of Histoplasma capsulatum infected mice, as well as the IL-2 content present in the supernatants of that cultures, were depressed along the first three weeks of the experiments, but starting week five, normal values were restored or even discretly increased. Incorporation of (³H) thymidine in histoplasmin stimulated lymphocytes remained inhibited along the seven weeks the experiment lasted. Results showed that inoculation of H. capsulatum yeast in mice provoked a temporary immunosuppression on cell mediated immunity, that can be explained by means of the inability of T cells to produce enough IL-2 necessary for the proliferation of T cells in culture.