Objectives: MRP8/ 14is a heterodimer of two myeloid calcium-binding proteins associated with different types of acute inflammatory processes. We studied MRP8/14 together with procaJcitonin (PeT) serum levels in order to diagnose infectious complications or the rejection process affecting kidney or heart allograft. Methods: A total of 419 serum samples was evaluated. MRP8/ 14 levels were measured by ELISA (BMA Biomed), PCT by a sensitive immunoluminiscent assay ILMA (Brahms Diagn.) Results: Both parameters showed very low basal levels in healthy subjects (range 303-1,660 ng/ml of MRP8/ 14; less than 0.08 ng/ml of PeT). A rapid increase in serum levels occurred in response to bacterial infections (MRP8/14 up to 6,230 ng/ml; PCT up to 297 ng/ml). Serum PCT concentration remained low in the presence of kidney allograft rejection, where MRP8/ 14 levels were increased. An uncomplicated outcome of kidney or heart transplantation did not change basal serum MRP8/ 14 and PCT levels. Conclusions: We condude that I) both MRP8/ 14 and PCT are very sensitive markers of complications in organ transplant recipients (normal values in uncomplicated outcome) 2) combination of both parameters is useful to discriminate between rejection (increased MRP8/ 14 with normal PeT) and systemic bacterial infection (both parameters increased).

Keywords: MRP8/ 14, procalcitonin, Inflammatory markers, Transplantation, Rejection