ELISA for LRPAP1 autoantibodies. (A) Representative ELISA of LRPAP1 autoantibodies in 76 sera samples of patients with MCL of whom 11 were positive for LRPAP1 antibodies. The columns represent the optical density measured at 490 nm. In total, in the sera of 41 of 312 patients, MCL autoantibodies directed against LRPAP1 were detected. (B) ELISA of immunoglobulin class of LRPAP1 autoantibodies. LRPAP1 autoantibodies belonged in 37 patients to IgG class and in 4 patients to IgM class. (C) ELISA for IgG subclasses of LRPAP1 autoantibodies: IgG LRPAP1 autoantibodies belonged in 25 cases to IgG1, in 7 cases to IgG2, in 4 cases to IgG3, and in 1 case to IgG4 subclass. (D) ELISA for the light chain of LRPAP1 autoantibodies: LRPAP1 autoantibodies were light chain–restricted (κ: 27; λ: 14). (E) Representative ELISA of titers of LRPAP1 antibodies in seropositive patients with MCL ranged between 1:400 and 1:3200. The curves represent OD measured at 490 nm with sera at indicated dilutions.