Detection of serum hemolysins in autoimmune hemolytic anemia.

Abstract Background Some patients with autoimmune hemolytic anemia (AIHA) have in their sera autohemolysins able to hemolyze RBCs in vitro by activation of complement. We describe three autohemolysins in patients with AIHA and we study clinical correlations. Study design and methods Thirty-two patients with AIHA were explored by immuno-hematological investigations (DAT, elution and serum testing). Results Three autohemolysins were detected in three patients. All of these autoantibodies were likely IgM and reacted in vitro only with enzyme-treated RBCs. Two warm autohemolysins were detected in patients with warm-type AIHA. The first one was active at neutral pH with low title. The second, having a wide thermal amplitude reacting at 22 °C and a title of 16, was acid. The hemolysin detected in patient 3 with cold hemagglutinin disease, was active at 4 and 22 °C, at acid pH. The thermal optimum was 4 °C and the title 64. It was also detected at 37 °C with the same title, but only at neutral pH. Conclusion Although these autohemolysins were incomplete, hemolyzing in vitro only enzyme-treated RBCs, they were associated for the three patients with severe hemolysis.