Interleukin-2 receptor (CD25) upregulation on human T-lymphocytes: sensitivity to immunosuppressants is defined by the mode of T-lymphocyte activation.

We investigated the transcription and expression of the interleukin-2 receptor (IL-2R, CD25) in human T-lymphocytes after different modes of T-lymphocyte stimulation in the presence of the immunosuppressants cyclosporin (CsA) and tacrolimus (FK506) as well as the structurally related macrolide rapamycin. We demonstrate that CsA and FK506 inhibited IL-2R (CD25) gene transcription and protein expression after stimulation by anti-CD3 or ionomycin, but not by phorbol ester or IL-2. Rapamycin, which does not affect IL-2 transcription, surprisingly inhibited IL-2R upregulation after anti-CD3- or ionomycin-induced stimulation, but not by phorbol ester or IL-2. Interestingly, the protein synthesis inhibitor anisomycin inhibited anti-CD3- or ionomycin-, but not phorbol ester- and IL-2-induced CD25 gene transcription indicating the dependence on de novo protein synthesis of the former pathways. These data suggest that the pharmacological effect of the imunosuppressants tested on IL-2R gene expression may be predicted by the requirement of protein synthesis of a given activation pathway.