[Autoimmune hemolytic anemias]

Autoimmune hemolytic anemias. Autoimmune hemolytic anemias (AIHA) are a rare cause of acquired hemolytic anemia, linked to the presence of an autoantibody directed against one or more antigens expressed on the surface of the red blood cell and certified by a positive direct antiglobulin test (DAT). AIHA can be non regenerative (10-20% of cases) and DAT may be negative (5% of cases). There are two main forms: warm antibodies AIHA (IgG positive TDA +/- C3d) and cold antibodies AIHA (C3d positive TDA), which differ in their underlying causes and treatment. Warm antibodies AIHA are in 50% of cases associated to B-cell chronic lymphoid leukemia, variable common immune deficiency, systemic lupus or drug; the treatment is based on short corticosteroid therapy (3 to 6 months) and rituximab is the 2nd line treatment. Cold antibodies AIHA are of two types: either post-infectious (mycoplasma, EBV), or linked to cold agglutinin disease that is indolent B clonal hemopathy; the treatment is primarily symptomatic and relies on cold protection measures. Corticosteroid therapy and splenectomy are ineffective. In cases of severe anemia, treatment with rituximab alone or in combination with chemotherapy is indicated.