High platelet turnover and reactivity in renal transplant recipients patients

Renal transplant recipients (RTRs) patients are at increased risk of cardiovascular morbidity and mortality. We aimed this study to assess reticulated platelets (RP), platelet reactivity and von Willebrand factor (vWF) levels in RTRs patients. In 150 RTRs patients [84 (56%) not on acetylsalicylic acid (ASA) treatment, group A; 66 (44%) on ASA 100 mg treatment, group B] and in 60 healthy control subjects, RP were measured by a Sysmex XE-2100 and were expressed as the percentage of RP of the total optical platelet count (immature platelet fraction; IPF), as the percentage of RP highly fluorescent (H-IPF) and as the absolute number of RP (IPF#). Platelet function was assessed by optical aggregometry (PA) induced by 1 mmol arachidonic acid (AA-PA), 2 and 10 mu M ADP (ADP2-PA and ADP10-PA) and 2 mu g/ml collagen (Coll-PA). vWF levels were measured by using a miniVidas analyser. Group A and group B showed significant higher values of RP than controls. At a multiple linear regression analysis IPF and IPF# were significantly and positively related to collagen-PA. By analysing group B according to residual platelet reactivity (RPR), we observed a significant higher number of RP among patients with RPR by collagen. Moreover at a multiple logistic regression analysis, IPF# significantly affected the risk of having a RPR by collagen. With regard to vWF, RTRs patients showed higher levels than control subjects. We documented a higher platelet turn-over in both groups of RTRs patients and increased platelet reactivity in RTRs patients not on ASA therapy than controls.