Tacrolimus inhibits NF-κB activation in peripheral human T cells

The calcineurin inhibitor, tacrolimus (TAC), inhibits the protein phosphatase activity of calcineurin, leading to suppression of the nuclear translocation of NFAT and inhibition of T cell activation. Apart from NFAT also the transcription factor NF-κB plays a key functional role in T cell activation. Therefore, blockade of the NF-κB activation cascade by immunosuppressive drugs prevents immune activation. Here we studied whether TAC blocks NF-κB activation in peripheral human T cells. After anti-CD3/CD28-activation of T cells from healthy volunteers, NF-κB (p65) phosphorylation was measured by flow cytometry in CD3+ T cells, CD4+ helper T cells and CD8+ cytotoxic T cells in the absence and presence of TAC 10 ng/mL, sotrastaurin 500 nM (positive control) and mycophenolic acid 10 µg/mL (negative control; n = 6). NF-κB transcriptional activity was measured by ELISA and intracellular TNFα protein, a downstream target, was measured by flow cytometry to assess the functional consequences of NF-κB blockade. Anti-CD3/28-activation induced NF-κB phosphorylation in CD3+ T cells, CD4+ T cells and CD8+ T cells by 34% (mean), 38% and 30% resp. (p