Paradoxical response to tacrolimus assessed by interleukin-2 gene expression.

Background: The calcineurin inhibitors cyclosporine and tacrolimus are potent immunosuppressive drugs, used mainly after organ transplantation. Methods to monitor their pharmacodynamic effects are not well established.

Methods: Whole blood samples from healthy volunteers (n = 16) were incubated for 24 hours in culture medium; each sample was preincubated for 2 hours with or without tacrolimus.