摘要：Intravenous injection of antigenic dose of sheep erythrocytes (SRBC)* into mice caused a 150-200% increase in plasma cyclic GMP level within 5 min which continued for 60 min thereafter. Immunization by soluble antigens such as dextran sulfate and bovine serum albumin also elevated cyclic GMP level in plasma. The plasma cyclic GMP increased by antigen stimulation might be derived from immunocompetent cells. This assumption was supported by several lines of evidence as follows : (1) rat erythrocytes which are less antigenic for mice caused a relatively low response in terms of increase in cyclic GMP compared with SRBC, (2) this cyclic GMP response was abrogated in animals under immunosuppressive states where X-irradiated, azathioprine-treated or tumor-bearing mice were used. Mice pretreated with agents which block autonomic nervous system functions develop normal plasma cyclic GMP responses upon SRBC injection. Our observation in this report and many in vitro studies by other investigators suggested that plasma cyclic GMP elevated by antigen stimulation may be mainly derived from lymphoid cells as a consequence of the triggering of immune response.
