Detection of antimoesin Abs in the sera of patients with AA, MDS-RA, and rheumatoid arthritis. (A) Detection of specific Abs to recombinant moesin in the sera of patients with AA. Purified recombinant native moesin protein was used to detect Abs specific to moesin in sera from 2 healthy persons (lanes 1-2) and 3 patients with PNH⁺ AA (lanes 3-5). Antimoesin monoclonal Ab was used as a positive control (lane 6). The serum of a patient with PNH⁺ AA diluted to 1:6400 was also used (lane 7). The arrow indicates recombinant moesin bands. (B-C) Titration of moesin Abs in sera of patients with AA and MDS-RA using ELISA. Antimoesin Ab titers were determined for the sera of 43 patients with PNH⁺ AA, 24 patients with PNH⁻ AA, 14 patients with PNH⁺ MDS-RA, 7 patients with PNH⁻ MDS-RA, and 48 healthy persons. (B) All patients. (C) Patients with recently diagnosed AA examined before therapy. (D-E) Titration of Abs specific to C-terminal moesin fragment in the sera of patients with AA and rheumatoid arthritis. Titers of anti–C-terminal moesin fragment Abs were determined in the sera of 62 patients with AA, 49 patients with rheumatoid arthritis, and 20 healthy persons. (D) Antimoesin C-terminal fragment (399-500) M1 Abs. (E) Antimoesin C-terminal fragment (494-577) M2 Abs. The solid line denotes a cutoff value defined as the mean + 2 SDs of the absorbance in healthy persons. P values indicate the differences in the prevalence of patients showing higher antimoesin or moesin-fragment Ab titers between 2 different groups.