Serum C-reactive protein. A useful and economical marker of immune activation in renal transplantation.

This study investigated whether serial daily measurements of serum C-reactive protein (sCRP) in 187 renal allograft recipients could help discriminate episodes of renal dysfunction due to rejection or cyclosporine (CsA) nephrotoxicity and help adjust immunosuppression in the early posttransplant period. Excellent primary graft function was associated with an initial peak of sCRP on day 2 after transplant (median, 29 microg/ml; range, 4 to >200 microg/ml) with a return to <20 microg/ml in all patients by day 5 (median, 7 microg/ml; range, 2-19 microg/ml). Stable graft function (mean creatinine, 155 microg/ml) was accompanied by a median sCRP of 4 microg/ml (range, 1-19 microg/ml). In 30 episodes of rejection responsive to methylprednisolone, sCRP was initially significantly raised to a median of 49 microg/ml (P<0.001) but fell rapidly in response to treatment to a median of 11 microg/ml and continued to fall. In 19 episodes of rejection unresponsive to methylprednisolone, median initial sCRP levels were significantly higher (P<0.001) at 119 microg/ml and were still at a median of 77 microg/ml at the end of the treatment. Twenty-four patients in whom renal dysfunction was associated with CsA nephrotoxicity showed no increase in sCRP concentrations; median sCRP concentrations remained at <5 microg/ml throughout the episodes. A similar pattern was seen in patients with acute tubular necrosis. Serial sCRP measurements provide economical and reproducible evidence of immune activation, help discriminate renal dysfunction due to CsA nephrotoxicity or rejection, and allow appropriate modification of immunosuppressive therapy.