Clinical and laboratory factors that affect the post-transfusion platelet increment.

Transfusion of platelet concentrates (PC) reduced the incidence of fatal hemorrhages in several thrombocytopenic conditions. Unfortunately, long-term platelet supportive care may be complicated by the development of a state of refractoriness, resulting in inadequate recovery of functional platelets. PC handling, clinical conditions of the patients and alloimmunization are the main factors affecting refractoriness. We evaluated the post-transfusion platelet increase in 25 patients (M=6, F=19) with hypomegakaryocytic thrombocytopenia receiving random ABO-compatible PC within 24 h after collection. Quality of PC was assessed by platelet count, pH measuring, LDH release, glycocalicin levels, CD-62 and CD-42b expression. Besides history, clinical status and therapy, we searched for the presence of anti-HLA class 1 and anti-HPA 1-4-5 antibodies. Only six patients (24%) were refractory to PC transfusion, as assessed by a corrected count increment (CCI)<5000. Four of such six patients (67%) had anti-HLA antibodies, as compared to zero of 19 responders (P<0.02). No other investigated clinical or laboratory feature was significantly different in refractory and responsive patients. Although post-transfusion bleeding time was shorter in responders than in refractory patients (297.33+/-249.95 versus 673.33+/-409.96; P<0.02), it did not significantly change even in patients with adequate correct count increment. Our data confirm the importance of anti-HLA antibodies in determining adequate post-transfusion recovery or refractoriness.