title: Immunopharmacodynamic evaluation of cyclosporine-treated renal allograft recipients.
abstract: Since the mode of action of cyclosporine (CsA) in man is incompletely understood, there are no monitoring tools to assess immunosuppressive effect in vivo. In vitro CsA inhibits lymphoproliferation in response to allogeneic and mitogenic stimuli, presumably due to reversible suppression of T helper cell generation of interleukin-2. Therefore the present studies examined the immunosuppressive effect of patient sera on a third-party mixed lymphocyte reaction (MLR) as a pharmacodynamic approach to quantify patient responses to CsA administration. Four kinetic patterns of in vitro immunosuppressive activity were discerned: 24/28 (86%) patients showing two cycles of MLR inhibition--namely, a first peak corresponding to absorption of CsA and an independent second peak of immunosuppression (type I), were free of rejection; while 17/23 (74%) patients demonstrating one cycle corresponding to the peak of CsA absorption (type II) suffered rejection episodes (P less than 0.001). In addition, 20 patients generating continuously high levels of in vitro serum activity (type III) were almost all free of rejection, but manifested nephrotoxicity; while two patients showing continuously low levels (type IV) suffered graft loss due to irreversible rejection (P less than 0.01). Thus failure to display either a second peak or continuously high levels of MLR inhibition was associated with a markedly increased incidence of rejection (76% versus 16%). The in vitro functional characteristics of peak-2 were similar to those of CsA, as assessed by the kinetics of inhibition of MLR lymphoproliferation or cell-mediated lympholysis (CML), and by gross chemical properties of partitioning into organic solvents and heat stability. These findings suggest that pharmacodynamic analysis by MLR inhibition not only affords a useful parameter of immunosuppression, but also may provide an in vitro model to dissect the generation and biotransformation of active CsA metabolites.
mesh_terms: D003524:Cyclosporins / Q000097:blood / Q000494:pharmacology / Q000627:therapeutic use*; D006084:Graft Rejection; D006801:Humans; D007111:Immunity, Cellular / Q000187:drug effects; D007376:Interleukin-2 / Q000276:immunology; D016030:Kidney Transplantation; D008213:Lymphocyte Activation / Q000187:drug effects; D007959:Lymphocyte Culture Test, Mixed; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D013696:Temperature
chemical_list: D003524:Cyclosporins; D007376:Interleukin-2