Cytopénies auto-immunes périphériques

Immune cytopenias constitute a difficult diagnostic and therapeutic challenge. Because of the heterogeneity of their etiologies and of their clinical presentations (infections, auto-immune and lymphoproliferative disorders), they are frequently underrecognized by nonspecialists. Nevertheless, immune cytopenias can be life threatening and require intensive care. Several mechanisms can account for hematopoietic cell destruction by the immune system. Pathogenic auto-antibody coated cells can undergo antibody-mediated lysis or phagocytosis. Blood cell destruction can also result from cell-mediated immune injury, through autoreactive cytotoxic T-lymphocytes or through the production of cytokines that inhibit hematopoiesis. This review will summarize the pathophysiological basis of peripheral auto-immune cytopenias and provide an overview of the various clinical presentations of immune-mediated destruction of platelets (immune-mediated thrombocytopenia, ITP), red blood cells (auto-immune hemolytic anemia, AIHA) and neutrophils (neutropenia associated with large granular lymphocytosis and antibody-mediated auto-immune neutropenia). The simultaneous or sequential immune destruction of several cell types (Evan's syndrome) will also be briefly discussed. The main diagnostic and therapeutic approaches will be summarized.