Chronic hemolytic anemia due to a monoclonal IgG cold agglutinin with anti-Pr specificity.

Immunologic studies performed in a case of autoimmune chronic hemolytic anemia with low titer cold agglutinins (1/16) demonstrated that the cold agglutinins corresponded to monoclonal IgG with anti-Pr specificity. This antibody had a large thermal amplitude, being active at 37 degrees C. These unusual characteristics may define a distinct subset of chronic cold agglutinin disease.