Anti-Hy, in the serum of a black man who had received multiple blood transfusions, was found to be a warm reactive and polyclonal IgG antibody which did not bind complement in vitro.51Cr-labeled Hy-positive red blood cells in the patient showed a shortened “2-component” survival curve. Hy antigens were not detected on leukocytes, platelets, or in the serum of Hy-positive individuals.
