Caractéristiques des anémies hémolytiques auto-immunes à anticorps « chauds » et du syndrome d’Evans de l’adulte

Abstract

The diagnosis of autoimmune hemolytic anemia (AIHA) relies mainly on the direct antiglobulin test (DAT), that is, Coombs' direct test, which has a sensitivity of about 95%. The classification of different forms of AIHA depends on the characteristics of the autoantibody and is an essential part of the diagnostic procedure. AIHAs mediated by warm-reactive autoantibodies (wAIHA) account for approximately 70% of all types: they may be either idiopathic or secondary to another autoimmune disorder (such as systemic lupus, lymphoma or primary immune deficiencies) or drug-induced. In adults, AIHA may also precede by many years the onset of non-Hodgkin lymphoma (NHL) or myelodysplastic syndrome. The management of wAIHA, based mainly on empirical data and uncontrolled studies, relies principally on corticosteroids as a first-line therapy. In cases of steroid resistance ( approximately 5-10% of the cases) and in cases of steroid-dependency, the most frequent second-line options are splenectomy or immunosuppressive agents. More recently, rituximab has shown promising results in small uncontrolled and retrospective studies and it is now widely used in refractory wAIHA. Future prospective studies should assess its efficacy earlier in the course of disease as a steroid-sparing strategy. Evans syndrome is an autoimmune disorder defined by the simultaneous or sequential combination of AIHA and immune thrombocytopenia or immune neutropenia. It may reveal an underlying condition (e.g., lupus, common variable immunodeficiency, etc.). Its management is usually extrapolated from the standard of care for isolated wAIHA. Before the availability of rituximab, the overall prognosis was relatively poor for adults with both wAIHA and ES, with a mortality rate of 15 to 20%.