<unk>  agglutinins, or<unk>  autoantibodies, occur naturally in nearly all individuals. These natural<unk>  autoantibodies occur at low titers, less than 1:64 measured at 4 °C, and have no activity at higher temperatures. Pathologic<unk>  agglutinins occur at titers over 1:1000 and react at 28-31 °C and sometimes at 37 °C.<unk>  agglutinin disease usually results from the production of a specific IgM antibody directed against the I/i antigens (precursors of the ABH and Lewis blood group substances) on red blood cells (RBCs).<unk>  agglutinins commonly have variable heavy-chain regions encoded by VH, with a distinct idiotype identified by the 9G4 rat murine monoclonal antibody.
Cold autoimmune hemolytic anemia
Warm antibody autoimmune hemolytic anemia
Acquired hemolytic anemia
Mixed autoimmune hemolytic anemia
Contaminated haemophilia blood products
Donath–Landsteiner hemolytic anemia
Drug-induced autoimmune hemolytic anemia
Drug-induced nonautoimmune hemolytic anemia