Role of cyclic AMP in antiserum-induced growth inhibition of murine leukemia L5178Y cells.

Heat-inactivated rabbit antiserum, in the absence of complement, induced a 1.5-2-fold increase in cyclic AMP levels in target cells L5178Y leukemia lymphoblasts within 10-20 min after the experiment. This change preceded the previously reported delayed inhibitory effects of antiserum on cell growth such as inhibition of RNA, DNA, and protein synthesis and cell proliferation, suggesting that cyclic AMP may be one of the mediators of the antigen-antibody reactions which occur at the cell surface. Furthermore, the addition of cyclic GMP or excess calcium to either antiserum or cyclic AMP-treated cultures alleviated the growth inhibitory effects of either antiserum or cyclic AMP, substantiating further the hypothesis proposed.