Thrombopoietin and thrombospondin in renal allograft recipients

Recipients of renal transplants appear to be at increased risk of thromboem bolic events. Despite accumulating evidence for the hyperreactivity of plat elets, the primary regulator of thrombopoiesis, thrombopoietin (TPO), has n ot yet been studied in renal transplant recipients. Thus, the aim of the pr esent study was to quantify the levels of TPO and to assess its contributio n to increased platelet reactivity in recipients of renal allografts. Serum concentrations of thrombospondin (TSP) were also determined in patients un dergoing renal transplants in order to evaluate the role of this multifunct ional protein in platelet hyperaggregability. Serum levels of TPO were sign ificantly lower in renal transplant recipients (n = 27) than in healthy con trols (30.8 +/- 20.6 pg/ml versus 129.9 +/- 113.6 pg/ml, P = 0.001). Serum concentrations of TPO were correlated neither with serum levels of creatini ne nor duration of transplantation. However, levels of TPO were negatively correlated with platelet counts (r = -0.50, P = 0.007) in recipients of ren al transplants. Plasma levels of TSP were higher in renal transplant patien ts than in the control group (104.5 +/- 54.7 ng/ml versus 63.4 +/- 41.5 ng/ ml, P = 0.003). No significant correlation was found between Levels of TPO and TSP. We conclude that, rather than the allograft function, the platelet mass determines the levels of TPO in recipients of renal transplants. Desp ite the low serum levels of TPO, and increased concentrations of TSP, TPO m ight still play a role in the hyperaggregability of platelets in patients u ndergoing renal transplants. Blood Coag Fibrinol 10:233-237 (C) 1999 Lippin cott Williams & Wilkins.