Pharmacodynamics of immunosuppressive drugs

The inability to measure the effects of immunosuppressive drugs on immune c ells in vivo has always severely limited preclinical drug development, the design and interpretation of clinical trials and the optimal clinical use o f this drug class in transplantation. Now, new technologies using microlite r samples of whole blood and exploiting the specificity, sensitivity and ve rsatility of flow cytometry have been developed. These novel techniques not only are illuminating the 'black box' that has obscured the pharmacodynami c effects of immunosuppressants but also are uncovering new mechanisms of a ction of these drugs. Pharmacodynamic assays measure biologically relevant events in vivo, since changes in lymphocyte functions in blood collected fr om immunosuppressed graft recipients faithfully reflect histopathologic eve nts within allograft tissue.