Rheumatoid factor isotypes and anti-agalactosyl IgG antibodies in systemic sclerosis

Abstract

Rheumatoid factor isotypes and anti-agalactosyl IgG antibodies (anti-AG IgG) have been reported to be detected and correlated with the disease activity in some collagen diseases. To study the frequency and the clinical significance of IgM, IgG and IgA rheumatoid factor (IgM-RF, IgG-RF and IgA-RF) and anti-AG IgG in patients with systemic sclerosis (SSc). Seventy-nine serum samples from patients with SSc were examined by specific enzyme-linked immunosorbent assays. The levels of IgM-, IgG-, IgA-RF and anti-AG IgG were significantly higher in SSc patients than in normal healthy controls. The levels of IgM- and IgA-RF were significantly higher in patients with diffuse cutaneous SSc than in those with limited cutaneous SSc. IgM-, IgG- and IgA-RF and anti-AG IgG were significantly elevated in 39%, 32%, 23% and 35% of 79 SSc patients, respectively. The prevalence of pulmonary fibrosis, oesophageal involvement and cutaneous telangectasias in patients with elevated IgA-RF levels was significantly higher than in those with normal levels. The incidence of pitting scars of digits in those with elevated IgG-RF levels and the incidence of contracture of phalanges in those with elevated IgM-RF levels were significantly higher than in those with normal levels. The frequency of increased erythrocyte sedimentation rate in patients with elevated IgG-RF and the frequency of increased C-reactive protein in those with elevated IgM-RF were significantly greater than in those with normal levels. IgM-, IgG-, IgA-RF and anti-AG IgG can be serum indicators of specific clinical manifestations in SSc patients.