Abstract
Autoantibodies are present in the serum of patients with autoimmune hemolytic anemia. Extensive serologic investigation is often needed to determine if alloantibodies are also present. To aid in the investigation, a simple method of serum dilution is described. The serum dilution method was compared to allogeneic red blood cell adsorptions in 119 cases tested over a two-year period. In 20 percent of the cases, the same underlying alloantibodies were detected by both the serum dilution method and allogeneic adsorption. In 42 percent of the cases, all autoantibody reactivity was removed by both methods. No clinically significant alloantibodies were missed using serum dilution as compared to allogeneic adsorptions. We conclude that serum dilution is a simple, rapid way to initially assess for the presence of alloantibodies that co-exist with autoantibodies.