Isolation, characterization, and molecular modeling of a rheumatoid factor from a Hepatitis C virus infected patient with Sjögren's syndrome.
We have previously isolated several IgG rheumatoid factors (RFs) from patients with both rheumatoid arthritis and idiopathic thrombocytopenia purpura using phage display system. To study IgG RFs in patients with other autoimmune diseases, phage display antibody libraries from a hepatitis C virus infected patient with Sjögren's syndrome were constructed. After panning, a specific clone RFL11 was isolated for characterization in advance. The binding activity and specificity of RFL11 to IgG Fc fragment were comparable to those of RFs previously isolated. The analysis with existed RF-Fc complex structures indicated the homology model of RFL11 is similar to IgM RF61 complex with high binding affinity of about 6 × 10⁻⁸ M. This effect resulted from longer complementarity-determining region (CDR) combining key somatic mutations. In the RFL11-Fc interfaces, the CDR-H3 loop forms a finger-like structure extending into the bottom of Fc pocket and resulting in strong ion and cation-pi interactions. Moreover, a process of antigen-driven maturation was proven by somatically mutated VH residues on H2 and H3 CDR loops in the interfaces. Taken together, these results suggested that high affinity IgG RFs can be generated in patients with Sjögren's syndrome and may play an important role in the pathogenesis of this autoimmune disease.
The Institute for Cancer Biology and Drug Discovery, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan ; Antibody and Hybridoma Core Facility, Taipei Medical University, Taipei 110, Taiwan.
Yu-Ching
YC
Lee
National Research Institute of Chinese Medicine, Taipei 110, Taiwan.
Keng-Chang
KC
Tsai
Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei 110, Taiwan ; Department of Microbiology and Immunology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 110, Taiwan.
Sy-Jye
SJ
Leu
Department of Laboratory Medicine, Mackay Memorial Hospital, Taipei 104, Taiwan.
Tuan-Jen
TJ
Wang
Department of Clinical Pathology, Cheng Hsin Rehabilitation Medical Center, Taipei 112, Taiwan ; Jen-Teh Junior College of Medicine, Nursing and Management, Miaoli County 356, Taiwan.
Chia-Yu
CY
Liu
Antibody and Hybridoma Core Facility, Taipei Medical University, Taipei 110, Taiwan ; School of Medical Laboratory Sciences and Biotechnology, College of Medical Science and Technology, Taipei Medical University, No. 250 Wu-Hsing Street, Taipei 110, Taiwan ; Department of Laboratory Medicine, Wan Fang Hospital, Taipei Medical University, Taipei 110, Taiwan.
Yi-Yuan
YY
Yang
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000378:metabolism; D000918:Antibody Specificity / Q000276:immunology; D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism; D061505:Cell Surface Display Techniques; D022801:Complementarity Determining Regions / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D017124:Conserved Sequence; D006526:Hepatitis C / Q000150:complications*; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000276:immunology / Q000378:metabolism; D007074:Immunoglobulin G / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019151:Peptide Library; D011485:Protein Binding / Q000276:immunology; D011487:Protein Conformation; D025941:Protein Interaction Mapping; D012217:Rheumatoid Factor / Q000737:chemistry* / Q000276:immunology* / Q000378:metabolism; D016415:Sequence Alignment; D057127:Single-Chain Antibodies / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D012859:Sjogren's Syndrome / Q000150:complications* / Q000276:immunology* / Q000378:metabolism
D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; D022801:Complementarity Determining Regions; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D019151:Peptide Library; D057127:Single-Chain Antibodies; D012217:Rheumatoid Factor