Epitope Mapping of SLE IgG Antiribosomal P Protein Antibodies (Anti-P) and Association of Epitope Anti-P React with and Clinical Findings in SLE

• Project/Area Number: 12670435
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 内科学一般
• Research Institution: Jichi Medical School
• Principal Investigator: TAKU Yoshio Jichi Medical School, School of Medicine, Instructor, 医学部, 講師 (20221666)
• Project Period (FY): 2000 – 2001
• Project Status: Completed (Fiscal Year 2001)
• Budget Amount: ¥3,300,000 (Direct Cost: ¥3,300,000); Fiscal Year 2001: ¥1,700,000 (Direct Cost: ¥1,700,000); Fiscal Year 2000: ¥1,600,000 (Direct Cost: ¥1,600,000)
• Keywords: ribosomal P protein / antiribosomal P protein antibodies / systemic lupus erythematosus / neuropsychiatric SLE / liver disease / mouse monoclonal antiribosomal P protein antibodies / 抗原認識部位

Research Abstract

Epitope Mapping of SLE Anti-P Antibodies. The binding sites on the carboxyl-terminal 11 amino acids (SDEDMGFGLFD) of human ribosomal P0 protein (P0-C-11) by IgG anti-P derived from patients with SLE were analyzed by a solid-phase ELISA using the synthetic peptides that correspond to P0-C-11, the carboxyl-terminal 7 (C-7 ; MGFGLFD), C-5 (FGLFD), C-3 (LFD), the internal 7 (P0-I-7 ; EDMGFGL), P0-I-5 (SDEDM). The epitopes with whichi SLE anti-P react were suggested to localized to C-3 and P0-I-7.
Association of Epitopes with disease activity and clinical findings. Each titer of IgG antibodies against P0-C-11, C-3, P0-I-7 and P0-I-5 was measured in sera from 80 patients with active SLE and association of these antibodies with disease activity and clinical findings was analyzed. Titers of antibody against P0-I-7 most significantly positive-correlated with SLE disease activity index scores among antibodies against 4 synthetic peptides. Titers of antibodies against P0-C-11, C-3 and P0-I-7 in patients with neuropsychiatric SLE (NPSLE) and in patients with liver disease not attributed to any cause other than SLE (SLE liver disease) were each significantly increased compared with patients without such findings. Anti-P against C-3 and P0-I-7 may be related to SLE activity and the pathogenesis of NPSLE and SLE liver disease.
Induction of Mouse Monoclonal Anti-P (MMo anti-P) and Epitope Mapping. Five MMo anti-P, which were induced by immunization with the peptide C-22 of Aretemia Sarina P2 (AS-C-22) and bound to AS-C-22 and P0-C-11 were shown to bind to P0-I-7 but not to other peptides (C-7, C-5, C-3 or P0-I-5). These results differed from those of SLE anti-p. The antigenesity of P0-I-7 may be stronger than that of C-3. Furthermore Four MMo anti-P induced by immunization with the peptide C-5 reacted with P0-C-11 and C-7 but not with C-5, C-3, P0-I-7 or P0-I-5. The affinity of C-7 against anti-C-5 may be stronger than that of C-5.