Warm antibody autoimmune hemolytic anemia

Autoimmune hemolytic anemia (AIHA) is a rare and heterogeneous disease that affects 1 to 3/100 000 patients per year. AIHA caused by warm autoantibodies (w-AIHA), ie, antibodies that react with their antigens on the red blood cell optimally at 37°C, is the most common type, comprising ∼70% to 80% of all adult cases and ∼50% of pediatric cases. About half of the w-AIHA cases are called primary because no specific etiology can be found, whereas the rest are secondary to other recognizable underlying disorders. This review will focus on the postulated immunopathogenetic mechanisms in idiopathic and secondary w-AIHA and report on the rare cases of direct antiglobulin test-negative AIHA, which are even more likely to be fatal because of inherent characteristics of the causative antibodies, as well as because of delays in diagnosis and initiation of appropriate treatment. Then, the characteristics of w-AIHA associated with genetically defined immune dysregulation disorders and special considerations on its management will be discussed. Finally, the standard treatment options and newer therapeutic approaches for this chronic autoimmune blood disorder will be reviewed.