Pharmacodynamics of T cell function for monitoring pharmacologic immunosuppression after allogeneic hematopoietic stem cell transplantation.

Information on pharmacodynamic monitoring after allogeneic hematopoietic cell transplantation (allo-SCT) to evaluate individual responses to immunosuppressive drugs is scarce. We studied the relationship between a panel of pharmacodynamic markers monitored during the first 3 months after transplant and the occurrence of graft-versus-host disease (GVHD). Lymphocyte activation assessed by intracellular ATP concentration in CD4(+) T cells, a high percentage of CD8(+) effector T cells, and a low percentage of CD4(+) regulatory T (Treg) cells correlated significantly with GVHD. A cutoff value of 0.5 for the CD8(+) effector T/Treg ratio provided the most accurate diagnosis of GVHD (sensitivity 58.8%, specificity 91%). These pharmacodynamic markers may provide an efficient complement to standard pharmacokinetic monitoring of immunosuppressive drugs after allo-SCT.