Emergence of Long-Lived Autoreactive Plasma Cells in the Spleen of Primary Warm Auto-Immune Hemolytic Anemia Patients Treated with Rituximab

Introduction: We recently proposed that B-cell depletion in immune thrombocytopenia (ITP) promotes the generation of long-lived plasma cells in the spleen, some of them being auto-reactive; but it remained possible that this observation was related to ITP itself rather than to B-cell depletion. Primary warm autoimmune hemolytic anemia (wAIHA) is a rare disease characterized by IgG auto-antibodies directed against antigens at the surface of red blood cells (RBCs) antigens, leading to their accelerated destruction. The use of B-cell depletion in wAIHA leads to 60 % to 70% of overall response at one-year and beyond. Nevertheless, 30-40 % of patients may resist to rituximab and then require a splenectomy. Nothing is known about antibody secreting cells (ASC) in the spleen of wAIHA patients, who have previously been treated or not with rituximab. In this study, we analyzed at the single cell level the splenic ASC from patients with chronic and active wAIHA, previously treated or not with rituximab (RTX), and we compared them with splenic ASC from ITP patients, and with splenic and bone marrow plasma cells from healthy donors (HD).