IMMUNOLOGICAL MECHANISMS IN COMMON RHEUMATOLOGIC DISEASES

Rheumatoid arthritis and seronegative spondyloarthropathies are rheuma tologic diseases that likely are caused by inflammatory reactions occu rring in genetically predisposed individuals mounting an immune respon se to an antigen, Understanding the immunopathology of these diseases provides insight into their etiology, pathogenesis, and a rationale fo r therapies targeting immune component interactions, Although the anti gen in rheumatoid arthritis is not known, several bacterial antigens h ave been associated with seronegative spondyloarthropathies, These ant igens result in an interaction between human leukocyte antigen-B27 res tricted CD8 positive T lymphocytes and the antigen presenting cell, pr oducing an inflammatory response, Rheumatoid factors are autoantibodie s directed against the fragment crystallizable portion of the immunogl obulin G. Rheumatoid factor immunoglobulin G immune complexes contribu te to the inflammatory events in the rheumatoid joint, and may play an important role in antigen presentation, A novel antigen capture enzym e linked immunosorbent assay was developed that mimicked B cell surfac e expressed rheumatoid factor, Conversely, a direct binding enzyme lin ked immunosorbent assay mimicked secreted rheumatoid factor, Compariso n of rheumatoid binding enzyme linked immunosorbent assays showed that the physical state of rheumatoid factor can affect binding characteri stics. The state of glycosylation of immunoglobulin G may contribute t o its antigenic structure, These physical characteristics may be impor tant in rheumatoid factor's pathogenic role in rheumatoid arthritis.