Abstract
The variation in the reactivity of [human] red blood cells (RBC) with HLA hemagglutinins was studied, and the influence of some variable factors evaluated. A comparison of the HLA reactivity of RBC with automated and manual methods, showed the superiority of the Auto-Analyzer technique. The similarity in the nature and behavior of HLA RBC antigens and the related Chido and Rg antigens was discussed. HLA antigens on RBC probably do not originate from serum-HLA-active substance. The strength of the HLA reactivity of RBC from a donor varied from time to time without evidence of clinical disease.