Background:~The immunosuppressive effect of both tacrolimus and cyclosporine is believed to be through inhibition of the enzyme calcineurin phosphatase (CaN) in T-lymphocytes. We have demonstrated, that tacrolimus decreases CaN activity in patients early after renal transplantation. In stable renal transplant patients treated this inhibition was hardly seen in patients treated with tacrolimus, while it was clearly demonstrated in patients treated cyclosporine. One explanation to this finding could be, that calcineurin phosphatase is up-regulated by long-term treatment with tacrolimus. The findings seem to imply, that tacrolimus has mechanisms of immunosuppression apart from inhibiting CaN. This could have implications for side-effects due to CaN inhibition. Among side-effects thought to be due to CaN inhibition is nephrotoxicity. The results may therefore be and indication of tacrolimus being less nephrotoxic compared to cyclosporine in long-term stable renal transplant patients.~Purpose:~The aim of the project is find out if long-term treatment with tacrolimus results in up-regulation of CaN in lymphocytes.~Study plan:~The general plan of the investigation is to compare CaN in lymphocytes in two groups of renal transplant patients treated with tacrolimus. One group just prior and just after transplantation compared to a group of stable renal transplanted patients a long time after transplantation. CaN is determined as enzyme activity, amount of protein, and by gen-activation.
The purpose of this study is to determine whether calcineurin phosphatase in the T-lymphocytes is up-regulated after long-term treatment with tacrolimus, a calcineurin inhibitor.