The in vivo survival of Co(a+b-) red cells in a patient with anti-Co^a was studied using a small aliquot of 51Cr-labeled red cells. The antibody reacted at room temperature without incubation and after completion of the antihuman globulin test with both reactions enhanced by ficin. Circulation of transfused cells was shortened with a T(50) of 5 min. The patient’s anti-Co^a titer rose following transfusion to 1:256. These data suggest that individuals with anti-Co^a should receive Co(a-b+) red cells for transfusion.

The in vivo survival of Co(a+b‐) red cells in a patient with anti‐Coa was studied using a small aliquot of 51Cr‐labeled red cells. The antibody reacted at room temperature without incubation and after completion of the antihuman globulin test with both reactions enhanced by ficin. Circulation of transfused cells was shortened with a T50 of 5 min. The patient's anti‐Coa titer rose following transfusion to 1:256. These data suggest that individuals with anti‐Coa should receive Co(a‐b+) red cells for transfusion.