Cyclosporine A

Cyclosporine A (CsA) is a neutral lipophilic compound first isolated in the 1970s from the fungal species Tolypocladium inflatum gams. CsA is a cyclic polypeptide consisting of 11 amino acids, with a molecular weight of 1202 daltons. It was found to have potent immunosuppressive properties and was initially used in the late 1970s to prevent organ rejection following transplantation. CsA first became available for general use in North America in 1983 and is now perhaps the most widely used drug to prevent graft rejection in transplantation medicine. The spectrum of conditions for which CsA is now being used has broadened, with reports of its benefit in several autoimmune and cutaneous diseases.

Cyclosporine A is an immunosuppressant that binds to the cyclophilin and inhibits phosphatase activity of protein phosphatase 2B (PP2B/calcineurin) with an IC50 of 5 nM. Cyclosporine A also inhibits CD11a/CD18 adhesion.