An immunochemical study of the synovial fluid can contribute to the distinction between rheumatoid and non rheumatoid arthritis.

Synovial fluids from 102 patients affected by various joint diseases have been analyzed for their protein, immunoglobulin and beta 2-microglobulin contents, for the total and alternative pathway hemolytic activities of the complement components, for the presence of rheumatoid factors and Clq binding materials. The aim of this study was to verify whether an immunochemical analysis of the synovial fluid could help to distinguish rheumatoid arthritis from other arthropathies. With regard to this, we emphasize that the latex test, the Clq binding assay, as well as the measurement of C3d and beta 2-microglobulin concentrations in synovial fluids, were the most helpful assays. An immunochemical synovial score was calculated summing the results of these four tests, thus making the recognition of rheumatoid arthritis, among the various inflammatory joint diseases, easier.