Antibodies to protein P in systemic lupus erythematosus.

A synthetic peptide was used to develop an enzyme linked immunosorbent assay (ELISA) to detect antibodies to the ribosomal proteins P0, P1, and P2. Significantly increased levels of IgG antibodies to protein P were found in 16% (18/116) of patients with systemic lupus erythematosus but slightly increased levels were detected in 2% (2/98) of patients with rheumatoid arthritis and one normal control subject. No association was observed between the presence of IgG antibodies to protein P and either lupus psychosis or depression. Sequential studies in individual patients failed to show an association between antibody levels and the development of psychosis.

Concentrations of glycosaminoglycans in synovial fluids and their relation with immunological and inflammatory mediators in rheumatoid arthritis.

The dimethylmethylene blue assay showed higher concentrations of glycosaminoglycans in many synovial fluids from patients with rheumatoid arthritis (RA) than in autologous sera or sera or synovial fluids from normal subjects. These results were taken to suggest that the glycosaminoglycans in RA synovial fluid were abnormally raised and derived from cartilage. To discover what stimulated such glycosaminoglycan release in RA joints relations were sought between synovial fluid concentrations of glycosaminoglycans and immunological and inflammatory mediators. It was shown that RA synovial fluid glycosaminoglycan concentrations correlated with synovial fluid C3d concentrations but not with synovial fluid rheumatoid factor concentrations, polymorphonuclear leucocyte numbers, myeloperoxidase concentrations, or the ability of the synovial fluids to release free radicals from normal polymorphonuclear leucocytes. A correlation was found between synovial fluid C3d and interleukin 1 concentrations as judged by both lymphocyte activating factor activity and immunoassay, but no significant correlation was detected between interleukin 1 and glycosaminoglycan concentrations. It is suggested that in the rheumatoid joint locally produced cytokines, in addition to interleukin 1, together stimulate glycosaminoglycan release from cartilage and render it vulnerable to attack by other processes.

Autoantibody analysis in chronic graft-versus-host disease.

Chronic graft-versus-host disease (cGVHD) bears clinical similarities to connective tissue diseases which are characterized by a spectrum of autoantibody formation. A wide range of autoantibody analyses in 19 allogeneic and 16 autologous bone marrow transplant (BMT) patients has determined that the most commonly detected antibody is IgM anti-cytoplasmic factor (ACF) occurring in 37% and 20% of allogeneic and autologous group respectively and of a type not normally seen in connective tissue disease. The antigen is as yet unidentified. These results suggest that autoantibody formation post-BMT is unrelated to the graft-versus-host process. Ophthalmic examination revealed evidence of a Sjögren-like syndrome in 20% autologous and 47% allogeneic patients, suggesting that the development of dry eyes post-BMT is not uniquely a feature of cGVHD.

Immunological involvement in the pathogenesis of pristane-induced arthritis.

Evidence is presented that the development of arthritis induced in mice by 2,6,10,14-tetramethylpentadecane (pristane) involves the immune response. Mice irradiated (500 rad) before injection of pristane failed to develop arthritis. By contrast, irradiated mice given lymphoid cells from normal donors and challenged with pristane developed arthritis. Other experiments showed that lymphoid cells from irradiated mice given pristane suppressed the development of arthritis in recipients challenged with pristane. Finally, the incidence of arthritis was significantly higher in CBA/Igb mice given pristane than in the allotypic congenic strain CBA/H, suggesting that a gene linked to the heavy chain immunoglobulin locus controls the development of arthritis.

Isolation and analysis of complement activating aggregates from synovial fluid of patients with rheumatoid arthritis using monoclonal anti-C3d antibodies.

The complement activating aggregates in synovial fluids of patients with rheumatoid arthritis (RA) have been isolated using monoclonal IgM anti-C3d antibodies attached to solid phases, and the content of the material bound has been analysed. High levels of aggregated IgG bearing C3d were found in RA synovial fluids, and IgG was the major immunoglobulin bound from such synovial fluids by anti-C3d Sepharose. A strong correlation was shown between levels of aggregated IgG bearing C3d and complement activation, as judged by C3d levels. Significant (but less strong) relationships were also observed between C3d levels and both complement consuming and C1q binding activity. C3d levels and levels of aggregated IgG bearing C3d were both significantly associated with the numbers of polymorphonuclear leucocytes (PMNs) found in RA synovial fluids. From these results it is concluded that the aggregated immunoglobulins bearing C3d (particularly IgG) isolated from RA synovial fluids are responsible for activating complement and attracting PMNs into the joint space. Radioimmunoassay showed no correlation, however, between levels of aggregated IgG (or IgM) bearing C3d and rheumatoid factor (RF) activity bound by anti-C3d. In addition, the material bound by anti-C3d Sepharose from most synovial fluid polyethylene glycol precipitates did not contain either IgM or IgG RF. Thus both techniques show that the majority of complexes bearing C3d do not contain RF. As the complement fixing aggregates apparently contain only immunoglobulin and complement components the results raise the problem of how the aggregates are formed. It is suggested that RA IgG may remain aggregated after either antigen or antibody (RF) has dissociated from the complex.