Quality assessment and transfusion efficacy of buffy coat-derived platelet concentrates washed with platelet additive solution

Background. Transfusion of washed platelet concentrates (W-PC) is recommended for some patients, such as those who have had previous severe allergic transfusion reactions. However, we still lack a standardised method for preparing these products. Here, we assessed the effect of a manual washing procedure on in vitro platelet quality and on the transfusion efficacy of W-PCs. Materials and methods. Buffy coat-derived W-PC in Composol solution were prepared by one-step centrifugation. Platelet activation and function were evaluated before and after washing by means of: (i) CD62 expression by flow cytometry; (ii) platelet aggregation (LTA); and (iii) the VerifyNow (R) P2Y12 test. A pilot prospective transfusion study was carried out in 11 onco-hematology patients receiving, in a short time, two consecutive transfusions: one with standard PC (S-PC) and one with W-PC. The post-transfusion platelet increment, the 1 h and 24 h corrected count increment (CCI) and occurrence of bleeding events were used as indices of transfusion efficacy. Results. Platelet recovery in W-PC was 84.8 +/- 5.4%. Washing slightly increased platelet activation in W-PC vs pre-washed samples (% CD62+ platelets 23.6 +/- 7 vs 14.8 +/- 1; p=0.03). As compared to prewash samples, platelet reactivity of W-PC as measured by VerifyNow (R) P2Y12 was significantly lower with ADP (PRU 32.2 +/- 37.7 vs 4.2 +/- 2.4, p=0.027), but similar using TRAP. Platelet aggregation responses to TRAP, collagen, ristocetin and arachidonic acid were maintained in W-PC. The pilot transfusion trial showed similar 1 h (13.5 +/- 5.6 vs 11.5 +/- 7.3, p=0.49) and 24 h (11 +/- 7.2 vs 9 +/- 6.5, p=0.48) CCI for S-PC and W-PC. Transfusion of W-PC was not associated with an increased number of bleeding events. Discussion. We have set up a simple method to obtain buffy-coat-derived W-PC, which has minor effects on in vitro platelet quality and transfusion effectiveness. This procedure can be easily implemented in transfusion centres for on-demand preparation of washed platelets.