The effect of lymphocytotoxic antibody reactivity on the results of single antigen mismatched platelet transfusions to alloimmunized patients

Despite selection strategies that attempt to maximize the platelet donor pool, significant numbers of alloimmunized patients have few if any available donors. Although the number of potential donors increases when one antigen mismatched platelet transfusions (OAMPT) are considered, transfusions from such donors are often cited to fail to produce satisfactory platelet count increments. The presence of lymphocytotoxic antibody (LCTAB) correlates well with responsiveness to random donor platelet transfusions and serves as a good serologic screen for the diagnosis of alloimmunization. We therefore reviewed the results of OAMPT to alloimmunized patients and assessed the relationship between LCTAB levels in the recipient and posttransfusion platelet count increments. We noted an unexpectedly high percentage of good responses in our patient population: 73% of all OAMPT to recipients with LCTAB < 60% reactive, resulted in successful increments. In recipients with LCTAB > or = 60%, 58% of all transfusions were still successful. Despite a statistically significant inverse relationship between the level of LCTAB and the response of OAMPT to alloimmunized patients, 58% to 73% of recipients will have a satisfactory platelet recovery posttransfusion. These data support extending donor searches for alloimmunized patients to include any single mismatch particularly if a recipient's LCTAB has lower reactivity.