Biological significance of the York, Cost, McCoy and Knops alloantibodies.

The biological significance of alloantibodies directed against the red blood cell antigens York, Cost, McCoy, and Knops has been investigated by means of a literature search and an analysis of 304 patient referrals received since 1965. Neither method detected documented cases of erythroblastosis fetalis due to these antibodies. The analysis of the patient referrals identified 11 women immunized by pregnancy. The literature search provided one documented case of hemolytic transfusion reaction and one probable case of successful transfusion of incompatible blood. The analysis of the patient referrals revealed two cases of probable successful transfusions of incompatible blood, nine patients with documented evidences of extravascular hemolytic transfusion reactions, and one patient with documented evidence of intravascular hemolytic transfusion reaction. The conclusion reached is that alloantibodies directed against the York, Cost, McCoy, and Knops antigens are biologically significant with respect to red blood cell transfusions in some patients. Transfusion practices show that most patients have received compatible transfusions, an indication that the physicians in the hospitals adhere to the philosophy of compatible transfusions, whenever possible.