Prion protein in patients with renal failure.

We previously found elevated levels of prion protein (PrP(C)) in the blood plasma of 16 patients with renal failure. We studied a further 20 patients with renal failure, and all had a significantly higher PrP(C) concentration than healthy normal subjects (P < 0.0001). Renal dialysis did not remove plasma PrP(C) in these patients. Because dialysis patients receive heparin during dialysis, which could potentially bind to PrP(C), the concentration of PrP(C) was measured in patients receiving heparin for cardiopulmonary bypass and was found to be similar to normal controls. We also studied several other groups with chronic illnesses and found that patients with thrombotic thrombocytopenic purpura and sickle cell anaemia had normal plasma PrP(C) levels, but that those with beta-thalassaemia had slightly elevated levels of plasma PrP(C). This suggests that the observations in renal failure were not just part of a generalized response to chronic illness or acute phase reaction. The mechanism of elevated plasma PrP(C) levels in renal disease is unknown, but this shows that plasma PrP(C) is not a specific marker of neurological disease or Creutzfeldt-Jakob disease.