[Effect of proteolytic enzymes on cyclic nucleotide levels and DNA synthesis in lymphocytes].

It is shown that the treatment of mouse spleen lymphocytes with the optimum mitogenic concentrations of thrombin and plasmin increases the intracellular amount of cGMP, the intracellular level of cAMP remaining the same. An increase of the intracellular level of cGMP and enhancement of the DNA synthesis in lymphocytes, on the one hand and the absence of these metabolic changes with the use of inactivated proteases, on the other, indicate that thrombin- and plasmin-induced proliferation of lymphocytes at the initial stages of cell activation is, probably, realized by the cGMP-dependent mechanisms.