Reassuring effect of pravastatin on natural killer cell activity in stablerenal transplant patients

Background. Administration of pravastatin soon after transplantation succes sfully lowers cholesterol levels, whereas a reduced number of acute rejecti on episodes is accompanied by a decrease in natural killer (NK) cell activi ty, As a consistent low NK cell activity caused by pravastatin might impair tumor surveillance leading to cancer, we studied the effect of pravastatin on NK cell activity in stable renal transplant patients. Methods, From 14 cyclosporine (CsA) treated and 11 azathioprine (AZA)-treat ed patients with hypercholesterolemia, more than 1 year after kidney transp lantation, we determined NK cell number and cytotoxic activity before, and at 6 and 12 weeks after, initiating pravastatin treatment, Additionally, ch olesterol levels and liver and kidney function parameters were assessed. Results. During pravastatin treatment, total cholesterol and low-density li poprotein cholesterol levels decreased significantly in both patient groups , In the CsA group, the number and cytotoxic activity of the NK cells at 12 weeks after institution of pravastatin was in the same range as before pra vastatin, Additionally, in the AZA group, pravastatin did not influence the number of NK cells. However, in the AZA group, both the number of NK cells and their cytotoxic activity were significantly (<0.002) lower compared to the values in the CsA group. Conclusions, In contrast to previous reports on decreased NK cell cytotoxic ity caused by pravastatin treatment early after transplantation, we cannot confirm these results in stable kidney recipients. In our hands, Mt cell cy totoxicity during pravastatin treatment was within the same range as in the absence of pravastatin. Thus, in view of the potential role of NK cells in tumor surveillance, these data are reassuring.