AUTOIMMUNITY part 70

Unlike cyclophosphamide and azathioprine, cyslosporin and tacrolimus (FK506) have immunosuppressive properties that are highly selective for T cells. Both agents interfere with the phosphatase calcineurin, ultimately leading to an inhibition of the activation of the transcription factor NFAT (nuclear factor of activated T cells). Cyclosporine binds to the intracellular protein cyclophilin and tacrolimus-FK binding protein complexes bind to calcineurin, preventing its activation by intracellular calcium, and the activation of NFAT. Although used most frequently to prevent transplant rejection, these agents have been shown to have activity in the treatment of RA, SLE, and certain forms of vasculities.