title: A functional variant of Fcgamma receptor IIIA is associated with rheumatoid arthritis in individuals who are positive for anti-glucose-6-phosphate isomerase antibodies.
abstract: Anti-glucose-6-phosphate isomerase (GPI) antibodies are known to be arthritogenic autoantibodies in K/BxN mice, although some groups have reported that few healthy humans retain these antibodies. The expression of Fcgamma receptors (FcgammaRs) is genetically regulated and has strong implications for the development of experimental arthritis. The interaction between immune complexes and FcgammaRs might therefore be involved in the pathogenesis of some arthritic conditions. To explore the relationship between functional polymorphisms in FcgammaRs (FCGR3A-158V/F and FCGR2A-131H/R) and arthritis in individuals positive for anti-GPI antibodies, we evaluated these individuals with respect to FCGR genotype. Genotyping for FCGR3A-158V/F and FCGR2A-131H/R was performed by PCR amplification of the polymorphic site, followed by site specific restriction digestion using the genome of 187 Japanese patients with rheumatoid arthritis (including 23 who were anti-GPI antibody positive) and 158 Japanese healthy individuals (including nine who were anti-GPI antibody positive). We report here on the association of FCGR3A-158V/F functional polymorphism with anti-GPI antibody positive status. Eight out of nine healthy individuals who were positive for anti-GPI antibodies possessed the homozygous, low affinity genotype FCGR3A-158F (odds ratio = 0.09, 95% confidence interval 0.01-0.89; P = 0.0199), and probably were 'protected' from arthritogenic antibodies. Moreover, among those who were homozygous for the high affinity genotype FCGR3A-158V/V, there were clear differences in anti-human and anti-rabbit GPI titres between patients with rheumatoid arthritis and healthy subjects (P = 0.0027 and P = 0.0015, respectively). Our findings provide a molecular model of the genetic regulation of autoantibody-induced arthritis by allele-specific affinity of the FcgammaRs.
authors.affiliation: Clinical Immunology, University of Tsukuba, Ibaraki, Japan. ismatsu@md.tsukuba.ac.jp
authors.forename: Isao
authors.initials: I
authors.lastname: Matsumoto
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Muraki
authors.forename: Taichi
authors.initials: T
authors.lastname: Hayashi
authors.forename: Takanori
authors.initials: T
authors.lastname: Yasukochi
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kori
authors.forename: Daisuke
authors.initials: D
authors.lastname: Goto
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ito
authors.forename: Akito
authors.initials: A
authors.lastname: Tsutsumi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Sumida
mesh_terms: D000328:Adult; D015703:Antigens, CD / Q000235:genetics*; D001172:Arthritis, Rheumatoid / Q000235:genetics / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D058851:GPI-Linked Proteins; D020022:Genetic Predisposition to Disease; D005838:Genotype; D005956:Glucose-6-Phosphate Isomerase / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic / Q000276:immunology*; D017452:Receptors, IgG / Q000235:genetics*
chemical_list: D015703:Antigens, CD; D001323:Autoantibodies; C428200:FCGR3B protein, human; D058851:GPI-Linked Proteins; D017452:Receptors, IgG; D005956:Glucose-6-Phosphate Isomerase