Low levels of lymphocyte MDR1 gene expression during early renal transplantation in patients treated with tacrolimus

P-glycoprotein (P-gp) is a membrane efflux pump increasing the transport of drugs such as tacrolimus out of the cells. The aim of the study was to determine the kinetics of lymphocyte P-gp expression in patients treated with tacrolimus during the first 3 months following renal transplantation. Lymphocyte MDR1 gene expression was measured by semi-quantitative RT-PCR a few hours before transplantation, 3 weeks and 3 months after the graft. Lymphocyte MDR1 gene expression was low in all the 10 patients compared to 10 healthy volunteers: 0.30 +/- 0.07 arbitrary units (patients) vs. 1.74 +/- 0. 55 (healthy volunteers) (P = 0.0002). MDR1 gene expression decreased among the patients during the study: 0.28 +/- 0.12 (3 weeks later) and 0.12 +/- 0.09 (3 months later) (P = 0.006). We can conclude that lymphocyte MDR1 gene expression among patients before renal transplantation is low and remains low during the first 3 months following the graft.