INHIBITION OF T-CELL CAMP FORMATION BY CYCLOSPORINE-A AND FH506

The influence of the immunosuppressants, cyclosporin A (CsA) and FK506 , on cAMP formation was studied in T cells from healthy controls and p atients with psoriasis. While basal cAMP levels were not affected, CsA (1 mu M) and FK506 (2 nM) prevented the isoprenaline (0.1 mu M)-induc ed increase in cAMP formation. Half-maximal inhibition by FK506 and Cs A was observed at about 0.2 nM and 20 nM, respectively. In addition, b oth agents significantly reduced (by about 50%) the forskolin 8 mu M)- stimulated cAMP formation. No differences were noted in cAMP responses (basal, stimulation by isoprenaline, inhibition by CsA and FK506) of T cells from healthy controls and psoriatic patients. We conclude that CsA and FK506 potently and efficiently interfere with the stimulatory adenylyl cyclase pathway in T cells and that regulation of T cell cAM P formation is apparently not altered in psoriasis.