INVITRO AND INVIVO CHARACTERIZATION OF THE ANTIINFLAMMATORY EFFECTS OF CYCLOSPORINE-A

Cyclosporin A (CsA), a cyclic undecapeptide extracted from Tolypocladium inflatum Gams, is effective in the prevention/treatment of graft rejection and in an increasing number of autoimmune and inflammatory disorders. The immunosuppressive effect of CsA was initially attributed to inhibition of lymphokine mRNA transcription. We have demonstrated that pharmacological concentrations of CsA (10-100 ng/ml) also inhibit the in vitro immunologic release of preformed (histamine) and de novo synthesized (leukotriene C4 and prostaglandin D2) mediators of inflammatory reactions from human basophils and mast cells. Furthermore, the administration of a single dose of CsA (7 mg/kg) to 8 normal donors caused a rapid and significant (20-40%) inhibition of histamine release from basophils obtained ex vivo from these subjects and challenged in vitro with anti-IgE, f-Met-Leu-Phe and A23187. The inhibitory effect of CsA peaked at 1-5 h, slowly decreased up to 13 h, and was associated with a sharp increase in blood CsA levels. Thus, CsA exerts remarkable antiinflammatory effects on the immunologic release of mediators from human basophils and mast cells - properties that may contribute to the drug's therapeutic effects.