Refractory Immune Hemolytic Anemia With A High Thermal Amplitude, Low Affinity IgG Anti-Pr_a Cold Autoantibody

Abstract

A 54 y.o. woman presented with acute Coombs-negative hemolytic anemia at an outside hospital where she received 25 RBC transfusions and did not respond to prednisone or splenectomy. On transfer to our hospital, routine DAT and IAT were weakly positive, occasionally negative. When a modified “cold” antiglobulin test was employed, the result was strongly positive for IgG, weakly positive for C3d. Cold agglutinin titer was 32, and the Donath-Landsteiner test was negative. The autoantibody exhibited Pr_a specificity.

The patient failed IV-IgG, high dose IV pulse steroids and cyclophosphamide, and continued to require daily transfusions. She responded 21 days after receiving daily plasma exchange (x3), with pulse cyclophosphamide on the third day, followed by escalating daily oral cyclophosphamide.

Key Words:

• Refractory autoimmune hemolytic anemia
• low affinity autoantibody
• wide thermal amplitude autoantibody
• Pr_a autoantibody specificity