Autoantibodies Directed Against Moesin C 471-577 /N 1-297 Are Novel and Specific Biomarkers of Immune Thrombocytopenic Purpura (ITP),

Abstract 3301 Moesin is a member of the protein 4.1 superfamily and shares structure homology with ezrin and radixin. The phosphorylation of moesin increases the aggregation of Fas, activation of capases, and triggers the apoptotic pathways through the Rho-ROCK pathway. The moesin protein is highly expressed in human platelets and phosphorylation of threonine558 is associated with the activation of platelets. Autoantibodies against moesin have not been evaluated in patients with ITP. Thus, we designed and expressed three polypeptides of moesin: N1-297 terminal, α 298–470 helix domain and C471-577 terminal for ELISA assays. Serum samples from patients with ITP (n=148), patients with non-immune thrombocytopenia (n=32), and other patients with hematologic diseases (n=102) as well as gender-matched healthy control subjects (n=50) were evaluated. All ITP patients clinically met an eligibility of ITP minimal standardized criteria from an international working group. 1 The titers of moesin autoanitbodies were significantly elevated in the sera from patients with ITP compared with healthy subjects (Mean of autoantibodies titers = N1-297 0.515/0.155; α298–470 0.252/0.159; C471-577 0.430/0.144, P Disclosures: No relevant conflicts of interest to declare.