In vivo survival of K:18 red cells in a recipient with anti-K18.

Red cell survival, IgG subclass, and mononuclear phagocyte assay studies were performed on a patient with an anti-K + K18 described previously. The 51Cr survival study with Kell negative K:18 red cells showed 76.6 percent survival at 75 minutes with 30.7 percent survival at 24 hours. The anti-K18 was characterized as IgG4 + IgG1. The mononuclear phagocyte assay was 16 percent when the serum was tested with K:18 cells. Among 54,450 ABO compatible donor units tested with this serum, no K:18- unit was found. These studies were undertaken to evaluate the clinical significance of the antibody when red cell support for a chemotherapy course was considered. Our data suggest that transfusion with K:18+ blood would be ineffective and could be used only to provide red cell support in an emergency should compatible units be unavailable.