Characterization of Autoantibodies in Mixed‐Type Autoimmune Hemolytic Anemia

Publisher Website
Google Scholar
Abstract
Three of 46 patients with autoimmune hemolytic anemia (AIHA) satisfied the diagnostic criteria for mixed‐type AIHA in which both warm‐type and cold‐type autoantibodies against red blood cells (RBCs) are present. The specificities of these autoantibodies were analyzed. All of the warm‐type autoantibodies were IgG‐x, and the specificities were not serologically classified. The autoantibody of patient 1 reacted to the 41‐ and 80‐kD peptides on immunoblotting, and the epitope corresponding to it was papain sensitive. Two warm‐type autoantibodies from patients 2 and 3 resembled each other in serological analyses and reacted with a protease‐ and neuraminidase‐resistant antigen. However, the antigen corresponding to the autoantibody of patient 3 was located on the 37‐kD peptide by immunoprecipitation. All of the cold‐type autoantibodies were IgM‐x and showed high titer and high thermal amplitude. According to the reaction pattern with untreated and enzyme‐treated RBCs, the cold‐type autoantibodies of patients 2 and 3 were revealed to be anti‐Om and anti‐I, respectively. In patient 1, the cold‐type autoantibody was characterized as having high affinity for autologous RBCs, but its specificity was unclassified. The antigens corresponding to the cold‐type autoantibodies were not located by immunoblotting and immunoprecipitation. These serological and immunochemical approaches to autoantibodies in mixed‐type AIHA revealed that the warm and cold components recognized the different antigens.