Immune complex-associated platelet disorder in renal allograft recipients

39 renal allograft recipients were selected on the basis of normal coagulation profiles and absence of detectable antiplatelet antibodies. Platelet aggregation to adenosine diphosphate was impaired in 10 patients and raised levels of immune complexes (IC) were present in 19 patients; between these two pathological parameters, a significant association could be found. Mean platelet serotonin content was significantly decreased in platelets of IC-positive patients compared to platelets of IC-negative patients or normal individuals. In vitro release of serotonin from normal platelets could be induced by addition of Raji cells which had been preincubated with IC-positive sera; this platelet defect may therefore represent an IC-induced functional abnormality.