Platelet crossmatches of single-donor platelet concentrates using a latex agglutination assay

A latex agglutination assay was evaluated for the purpose of identifying compatible platelet donors for alloimmunized recipients. Assay reagents were prepared by adsorbing detergent-solubilized, donor- specific platelets to polystyrene latex beads. Semiquantitative results for up to 30 donors can be completed in less than 1 hour. These reagents retained their immunoreactivity for at least 3.5 months. A retrospective study has established the assay's upper limit of compatibility. The prospective study evaluated transfusions to a group of multiply transfused patients. Part I evaluated 143 crossmatched, single-donor platelet transfusions given to 50 patients. In 96 percent of the cases, a positive crossmatch was associated with an unsuccessful transfusion outcome; in 84 percent of the transfusions, a negative crossmatch predicted a satisfactory platelet increment. The overall predictability, sensitivity, and specificity were 87, 62, and 99 percent, respectively. Part II evaluated 105 transfusions given to the 43 patients (of 50) in whom no incidence of fever, sepsis, or bleeding could be documented. A positive crossmatch was 96-percent efficient in predicting an unsuccessful transfusion, whereas a negative crossmatch was associated with an adequate platelet increment following 89 percent of the transfusions. The overall predictability was 91 percent, the sensitivity was 72 percent, and the specificity was 99 percent. Within- run and between-run variations were 6.3 and 6.2 percent, respectively. These results demonstrate that detergent-solubilized platelet antigens, immobilized on latex particles, can be used in a cost-effective crossmatching procedure.