Immune Hemolysis: Diagnosis and Treatment Recommendations

Autoimmune hemolytic anemia (AIHA) is a heterogeneous disease usually classified as warm, cold [cold agglutinin disease (CAD)] or mixed, according to the thermal range of the autoantibody. Diagnosis is based on the direct antiglobulin test (DAT), typically positive with anti-IgG antisera in warm AIHA and anti-C3d in CAD. Diagnostic pitfalls are due to IgA autoantibodies, warm IgM, low-affinity IgG, or IgG below the threshold of sensitivity, and about 5% of AIHA remains DAT-negative. The treatment of AIHA is still not evidence-based. Corticosteroids are the first-line therapy for warm AIHA. For refractory/relapsed cases, the choice is between splenectomy (effective in ~70% cases but with a presumed cure rate of 20%) and rituximab (effective in ~70%-80% of cases), which is becoming the preferred second-line treatment, and thereafter any of the immunosuppressive drugs (azathioprine, cyclophosphamide, cyclosporine, mycophenolate mofetil). Rituximab is now recommended as first-line treatment for CAD. Additional therapies are intravenous immunoglobulins, danazol, and plasma exchange, with alemtuzumab and high-dose cyclophosphamide as the last options.