The antagonistic action of cyclic GMP and cyclic AMP on proliferation of B and T lymphocytes.

The effect of c-AMP, c-GMP and both substances together on (3H)-thymidine incorporation into nuclear DNA was investigated using spleen cells of normal and athymic nude mice. c-GMP induces DNA synthesis in both normal and nude spleen cell populations. c-AMP inhibited the stimulatory activity of c-GMP as well as the phytohaemagglutinin (PHA) and lipopolysaccharide (LPS) response of spleen cells. The inhibitory activity of c-AMP on the PHA and LPS responses can be reversed by c-GMP. The possible role of cyclic nucleotides in the regulation of cell proliferation and of the immune response is discussed.