Immunofluorescence of synovial membrane multifactorial analysis of the results.

: Synovial membrane taken by needle biopsy from the knee joint of 61 patients with various rheumatic diseases were studied using immunofluorescence methods. Staining techniques and their controls were detailed. Classical statistical tests and principal components multifactorial analysis of the data emphasized some differences between the pathological groups. Connective tissue diseases seemed to be characterized by plasma cells fluorescence and mixed immunoglobulins and complement deposits. These were mostly localized to extracellular spaces in sero-positive rheumatoid arthritis and to blood vessels in sero-negative rheumatoid arthritis and systemic lupus erythematosus. On the contrary, isolated immunoglobulins without complement were mostly found in the other inflammatory arthritis, while negative results were obtained in non inflammatory arthropathy. Immunoglobulin classes did not seem to have any diagnostic value. On the contrary, rheumatoid factor was specific for rheumatoid arthritis, whatever the serological pattern was, and it was particularly frequent in patients suffering from rheumatoid arthritis associated with a Sj5AOGREN SYNDROME. A strict relationship between classical histological findings and immunofluorescence results was not always found; so, immunological methods can be aquivocal.