Cyclosporine: a new and promising immunosuppressive agent.

Cyclosporine is an exciting new agent that has been heralded as a major advance in chemical immunosuppression for organ transplantation. The drug is a potent, reversible suppressant of both humoral and cellular immunity and does not cause myelosuppression. Its mechanism of action appears to be selective for lymphocytes and may interrupt the necessary cellular signals required for proliferation of alloreactive T-cells. In early clinical trials cyclosporine has been shown to ameliorate renal allograft survival. A major concern about its widespread clinical use has been the observed nephrotoxicity and possible development of lymphomas in treated patients. Adverse side effects may be minimized by pharmacologic monitoring of drug levels. Future questions include the ideal dosage schedule, necessity for additional immunosuppressive agents, distinction between nephrotoxicity and rejection, and the precise mode of absorption, accumulation, and metabolism of the drug. Cyclosporine may be considered the prototype of a new generation of immunosuppressive agents that open up new perspectives in the field of immunoregulation. The ability to synthesize the compound may permit future biochemical manipulations to increase the immunobiologic specificity and decrease the toxicity of the drug.