Characterisation of non-histone nuclear proteins cross reactive with purified rheumatoid factors

Cross-reactive rheumatoid factors in rheumatoid arthritis with extra-articular disease

Rheumatoid factors (RF) have been shown to have considerable heterogeneity and bind with IgG as well as with a variety of substances such as nuclear histone, non-histone nuclear protein, nitrophenyl groups or ssDNA. We describe evidence that polyclonal RF cross-reactive with ssDNA (CRRF) are widely distributed in a variety of rheumatic diseases, and that their serum level is significantly higher in rheumatoid arthritis (RA) with extra-articular disease. Although the mechanism of the cross-reactivity is not clear, the presence of CRRF could be a serological feature of a clinical subset of RA. The high prevalence rate of CRRF in RA with extra-articular disease also suggests its pathogenetic role in the extra-articular manifestation of this disease.

Antihistone antibodies in rheumatoid arthritis and Felty's syndrome

Although antihistone antibodies are frequently detected in patients with systemic lupus erythematosus, they appear to be uncommon or present only at low levels in rheumatoid arthritis (RA) patients. We used an enzyme-linked immunosorbent assay to study sera from 42 patients with RA, and we confirmed that antihistone antibodies mainly occurred at low levels in these patients. In contrast, 83% of 24 patients with Felty's syndrome had antihistone antibodies, often at high levels. Thus, antihistone antibodies may be a common autoimmune abnormality in patients with Felty's syndrome but not in other patients with RA. In addition, we demonstrated that some rheumatoid factors have cross-reactive antihistone antibody activity.

Persistence of collagen type II-specific T-cell clones in the synovial membrane of a patient with rheumatoid arthritis

Rheumatoid arthritis is an autoimmune disease characterized by T-cell infiltration of the synovium of joints. Analysis of the phenotype and antigen specificity of the infiltrating cells may thus provide insight into the pathogenesis of rheumatoid arthritis. T cells were cloned with interleukin 2, a procedure that selects for in vivo-activated cells. All clones had the CD4 CDW29 phenotype. Their antigen specificity was tested by using a panel of candidate joint autoantigens. Four of 17 reacted against autologous blood mononuclear cells. Two clones proliferated in response to collagen type II. After 21 months, another set of clones was derived from synovial tissue of the same joint. One of eight clones tested showed a strong proliferative response against collagen type II. The uncloned synovial T cells of a third operation from another joint also responded to collagen type II. The persistence of collagen type II-specific T cells in active rheumatoid joints over a period of 3 years suggests that collagen type II could be one of the autoantigens involved in perpetuating the inflammatory process in rheumatoid arthritis.

The MRL-lpr/lpr mouse. A model for the study of rheumatoid arthritis

Autoimmune MRL-lpr/lpr mice develop a spontaneous destructive arthropathy sharing some features with rheumatoid arthritis including synovial cell proliferation, pannus formation, rheumatoid nodule-like lesions and circulating rheumatoid factors. Rheumatoid factors elaborated by MRL-lpr/lpr mice exhibit binding characteristics similar to those found in the sera of patients with rheumatoid arthritis; however, these autoantibodies do not appear to be essential for the induction of arthritis in MRL-lpr/lpr mice. Molecular studies, indicating that VH genes from several VH families are capable of encoding these rheumatoid factors, argue against the existence of unique "autoantibody genes" in the germline of MRL-lpr/lpr mice. Although the mechanisms underlying cartilage injury in MRL-lpr/lpr mice have not been elucidated, available evidence suggests that invading synovial cells play an important role. Delineation of the cellular and molecular mechanisms responsible for articular destruction in MRL-lpr/lpr mice may provide important insights concerning the pathogenesis of rheumatoid arthritis.

Human-human hybridoma autoantibodies with both anti-DNA and rheumatoid factor activities

Human hybridomas have been produced by fusing peripheral blood lymphocytes from patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) with the GM 4672 human cell line. 262 hybridoma clones from the fusions of four RA and five SLE patients were screened for binding to denatured DNA (dDNA), native DNA, and the Fc fragment of human IgG (HIgG). Of the 17 hybridoma antibodies (nine RA, eight SLE) selected for strong binding to denatured DNA, Fc, or both, five reacted with dDNA only, one with Fc only, and eight with both dDNA and Fc. Hybridoma supernatants exhibiting dual reactivity were absorbed over HIgG and bovine serum albumin (BSA)-Sepharose immunoabsorbent columns. The reactivities to both DNA and HIgG were completely removed by the HIgG column but unaffected by passage over the BSA column, and both DNA binding and rheumatoid factor activities were recovered in the acid eluates from the Sepharose-IgG column. The binding of dual reactive hybridoma autoantibodies to the Fc fragment of HIgG was specifically competed by dDNA and HIgG, providing additional evidence that one antibody may be capable of reacting both as a rheumatoid factor and as an anti-DNA antibody.