Role of cyclic AMP on differentiation of T- and B-lymphocytes during the immune induction.

Spleen cell cultures from genetically thymus-deficient nude mice were restored with a T-cell replacing factor obtained from normal spleen cells of Balb/c-Ig^b mice stimulated with concanavalin A. Treatment of these cultures with an inhibitory dose of cyclic AMP did not result in reduction of the number of specific antibody-forming cells after stimulation by antigen, whereas the same treatment led to inhibition in cultures restored with normal hydrocortisone-resistant thymus lymphocytes. Further experiments lead to the conclusion that the early effect of cAMP on the immune induction seen in vitro reflects inhibition of the production or secretion of a T-cell factor which is a prerequisite for triggering B-cells with a thymus-dependent antigen.