Crossmatch compatible blood for patients with anti-P1.

Anti-P1 is a cold-reactive antibody often found in the serum of P2 individuals. For the past two years our reference laboratory has encouraged the use of crossmatch compatible blood for patients with Anti-P1 rather than the use of reagent-typed P1 negative units. The authors recently surveyed those hospitals that referred patient samples with anti-P1 to determine the safety of blood selected in this manner. Nineteen patients received 53 units without incident using this procedure. This report is a summary of the authors' findings.