Significance of rheumatoid factor isotypes in seronegative rheumatoid arthritis

Abstract

In a cross-sectional study of 124 patients with definite or classical rheumatoid arthritis (RA) and negative agglutination assays, rheumatoid factor (RF) isotypes were measured using an ELISA technique. Elevated levels of IgA-RF were found in 55 patients (44%), IgG-RF in 99 (80%), and IgM-RF in 20 (16%). The levels of IgA- and IgM-RF correlated with each other (P less than 0.001). Elevated levels of IgM-RF were associated with a more severe disease course. Elevated levels of IgA-RF correlated with the occurrence of bone erosions. The results of this study suggest that in patients with RA and negative agglutination assays, both IgM- and IgA-RF are markers of disease severity.

Rheumatoid factor isotypes, disease activity and the outcome of rheumatoid arthritis: Comparative effects of different antigens

“…Studies relating RF isotypes RA severity and out-IgG as antigen there was an association between come have given conflicting results; Table VII sum-IgARF and rheumatoid nodules (p<0.02). There marises 25 studies involving 1894 patients (7-10, was no association when horse IgG was antigen 13-16, [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]. Thirteen used rabbit IgG as the ( Table VI ).…”

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

“…IgG isotype RF (IgG‐RF) is present in abundant quantities in the joint cavity and undergoes self association into dimers or higher polymers. Some investigators reported that the levels of serum IgG‐RF were related to the disease activity in rheumatoid arthritis (RA); 6–8 others reported to the contrary 9–11 . The clinical significance of IgA‐RF, which can be measured by a similar method to IgG‐RF, has not been well established.…”

Synovial tissue macrophages and joint erosion in rheumatoid arthritis.

“…Among the features which have been repeatedly associated with more rapid or extensive joint erosion are greater disease activity in the early stages,6 7 the appearance of nodules8 10 and serum levels of IgM-_8 and IgA-rheumatoid factor (RF). [14][15][16][17][18] Previous studies seeking predictors of the radiological course in RA have not included immunohistochemical analysis of the synovial membrane. It is entirely appropriate to study synovial immunohistochemistry as the synovial membrane contains all the interrelated cellular and biochemical elements which lead to tissue destruction.…”