Anti-heat shock protein 70 kDa and 90 kDa antibodies in serum of patients with rheumatoid arthritis

Objectives-Stress proteins (HSPs) are highly conserved immunodominant antig ens found in various species. The purpose of this study was to assess the p revalence and prognostic significance of antibodies to HSC 70 kDa and HSP 9 0 kDa in three groups of patients with longstanding rheumatoid arthritis (R A) defined based on the severity of articular erosions. Methods-73 patients with longstanding (> 6 years) RA whose HLA-DR genotype was known were divided in three groups according to Larsen's score and comp ared with 47 recent onset (<1 year) RA patients and with control groups com posed of patients with other inflammatory diseases (n=137) or of normal con trols (n=48). IgGs and IgMs to HSC 70 kDa and HSP 90 kDa were determined us ing an ELISA with purified bovine HSC 70 kDa or HSP 90 kDa. Results-Concentrations of IgGs and IgMs to HSC 70 were significantly increa sed in 41.1% and 42.5% of longstanding RA patients, respectively. Correspon ding figures for IgGs and IgMs to HSP 90 were 39.7% and 56%. IgMs to HSC 70 and HSP 90 were less frequent in recent onset RA (19% and 13% respectively ). Among the groups with other inflammatory diseases, only the MCTD group e xhibited high frequencies of IgGs to HSC 70 (80%) and HSP 90 (85%). DRB1*04 01 positive RA patients (n=23) were not more likely to have increased conce ntrations of antibodies to HSC 70 kDa or HSP 90 kDa than other RA patients (DR4 positive but DRB1*0401 negative, or DR1 positive, n=31; or negative fo r both DR4 and DR1, n=14). IgGs to HSP 90 kDa were significantly more frequ ent (p<0.05) in longstanding RA patients whose Larsen's score was 4 or more (57%) than in those whose Larsen's score was 2 or 3 (39.4%) or less than 2 (16%). No associations were found between Larsen's score and IgGs or IgMs to HSC 70 kDa or IgMs to HSP 90 kDa. A significant correlation was demonstr ated between IgGs to HSP 90 kDa and two other serological markers for RA, r heumatoid factor, and anti-Sa antibody; there were no correlations with ant ikeratin antibody, antiperinuclear factor, or anti-RA 33. Conclusion-IgGs to HSP 90 kDa are most common in longstanding RA patients w ith articular erosions, suggesting that they may be related to the articula r prognosis in RA.