Relationship between antinuclear antibodies and differential cell counts in synovial fluid of patients with rheumatoid arthritis.

Presence and titres of organ non-specific and granulocyte-specific antinuclear antibodies (ON-ANA and GS-ANA) were studied in 100 samples of synovial fluids taken from 95 patients with seropositive rheumatoid arthritis and in corresponding sera. At the same time the white cell count as well as the percentage of granulocytes and granulocytes with pycnotic or fragmented nuclei (PGS and FGS, respectively) were evaluated in the synovial fluid sediment. Twenty six percent of synovial fluid samples were positive for ON-ANA and the same percentage of samples were positive for GS-ANA. Titres of GS-ANA showed a clear inverse correlation with the number of granulocytes. The rate of PGS as well as of FGS increased with the titer of both types of studied ANA, however, a significant correlation was observed only between the percentage of these cells and GS-ANA. Differences in specificity and titres of ANA were demonstrated in samples of synovial fluids taken at the same time from both knee joints of 5 patients under study. The differences were also noticed when the specificity and titer of ANA present in synovial fluid and serum samples were compared. A case of rheumatoid arthritis showing sudden appearance of numerous plasma cells in the synovial fluid in course of the disease is presented. This patient initially had no ANA in the synovial fluid or in serum, but ANA were detected at the time of synovial fluid plasmacytosis. These data indicate that a local production of ANA is likely to take place in ANA positive rheumatoid arthritis.