Platelet Activation Following Exposure to Anti-ABO Antibodies-An In Vitro Study.

Since platelets possess A and B antigen, mismatched ABO platelets could, theoretically, become activated or hypofunctional by exposure to anti-A or anti-B antibodies found in transfused or recipient plasma. Following normal baseline platelet aggregation to adenosine diphosphate (ADP), platelets from normal donors of different blood types were incubated at 37°C for 10 minutes with 50µl of normal saline (NS), O plasma, or AB plasma. Aggregation was then induced with ADP. No significant changes from baseline were seen in platelet aggregation studies following incubation with NS. However, platelet aggregations of type A and type B platelets were significantly inhibited when incubated with O plasma (mean of 41 and 22%, respectively). Our findings indicate that mediators in group O plasma, very likely anti-A and anti-B antibodies, cause impaired platelet aggregation of ABO non-identical platelets.

An association of ABO non-identical platelet and cryoprecipitate transfusions with altered red cell transfusion needs in surgical patients.

BACKGROUND: Transfusion of ABO non-identical plasma, platelets and cryoprecipitate is routine practice even though adverse effects can occur. METHODS AND MATERIALS: Our hospital changed transfusion practice in 2005 and adopted a policy of providing ABO-identical blood components to all patients when feasible. We retrospectively compared the transfusion requirements, length of stay and in-hospital mortality in relation to ABO blood group in surgical patients who received platelet transfusions before and after this change to determine whether it resulted in any benefit. RESULTS: Prior to the change in practice, both group B and AB patients received more ABO non-identical platelet transfusion (P=0·0004), required significantly greater numbers of red cell transfusions (P=0·04) and had 50% longer hospital stays (P=0·039) than group O and A patients. Following the policy change, there was a trend for fewer red cell transfusions (P=0·17) and length of stay in group B and AB patients than group O or A patients. Overall, the mortality rate per red cell transfusion decreased from 15·2 per 1000 to 11·0 per 1000 (P=0·013). CONCLUSIONS: These results, in the context of previous findings, suggest that providing ABO-identical platelets and cryoprecipitate might be associated with reduction in transfusion requirements and improve outcomes in surgical patients.