Cytokine inhibition of DNA synthesis: effect on cyclic adenosine monophosphate in lymphocytes.

A greater than twofold increase in intracellular adenosine 3',5'-monophosphate (cyclic AMP) inhibited DNA synthesis, in stimulated rat lymphocytes. A two- to fourfold rise of intracellular cyclic AMP, starting at 16 hours, was produced by purified inhibitor od DNA synthesis added to such cells either at 0 or 16 hours, in close association with the initiation of DNA synthesis.