title: Rheumatoid factor isotypes in mixed connective tissue disease.
abstract: Mixed connective tissue disease (MCTD) is a connective tissue disorder that is often accompanied by various immunological abnormalities. In this study, we analyzed serum levels of rheumatoid factor (RF) isotypes in patients with MCTD and in normal controls to determine if any of these isotypes reflects the severity of the disease. IgM-RF, IgG-RF, and IgA-RF were positive in 48, 38, and 33% of the patients, respectively. The frequency of positive anti-SS-A antibody and decrease in white blood cell counts were significantly greater in patients with elevated IgA-RF levels than that in those with normal levels. These results suggest that the presence of RF isotypes can be regarded as one of the various immunological abnormalities of MCTD.
authors.affiliation: Department of Dermatology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan. in-der@h.u-tokyo.ac.jp
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Mimura
authors.forename: Hironobu
authors.initials: H
authors.lastname: Ihn
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Jinnin
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Asano
authors.forename: Kenichi
authors.initials: K
authors.lastname: Yamane
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Tamaki
mesh_terms: D000328:Adult; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007132:Immunoglobulin Isotypes / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood; D008297:Male; D008947:Mixed Connective Tissue Disease / Q000097:blood / Q000175:diagnosis / Q000276:immunology*; D012016:Reference Values; D012217:Rheumatoid Factor / Q000097:blood* / Q000145:classification
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007132:Immunoglobulin Isotypes; D007075:Immunoglobulin M; D012217:Rheumatoid Factor