Transfusion of incompatible RBCs to a patient with alloanti-Kp(b)

BACKGROUND: The finding of an antibody that reacts against a high-incidence blood group antigen always constitutes a complex transfusion problem becau se of the difficulty in finding compatible units. When the transfusion of i ncompatible RBCs is imperative, it would be of great interest to have acces s to techniques facilitating the prediction of the transfusion outcome. STUDY DESIGN AND METHODS: The case of a patient with alloanti-Kp(b) who req uired RBC transfusions is reported. The functional activity of this antibod y was assessed by both the chemiluminescence test (CLT) and the survival of Cr-51-labeled RBCs. RESULTS: The CLT showed an opsonic index of 0.8 with Kp(b)-positive RBCs (n ormal values up to 1.6) in pretransfusion studies. During an elective surgi cal procedure, the patient required the transfusion of one incompatible uni t of RBCs, which did not produce hemolysis, Two weeks after this incompatib le transfusion, the opsonic index had risen to 11. Results of the Cr-51 in vivo study, also performed at that time, indicated 24.3 percent survival of Kpb-positive RBCs at 60 minutes and 2.0 percent at 24 hours. CONCLUSION: Results of the CLT correlated with the in vivo transfusion outc ome and later with the Cr-51 survival study.