Oncoprotein expression in human synovial tissue: an immunohistochemical study of different types of arthritis.

Based on the fact that synovial lining cells have some properties of transformed-appearing cells, we have examined the expression of Myc, Myb, Fos, Jun and Ras oncoproteins in synovial tissues from patients with different types of arthritis. Formalin-fixed and paraffin-embedded sections of synovial tissue from 12 patients with rheumatoid arthritis (RA), 14 with reactive arthritis (ReA), nine with other seronegative arthritis (OSA), seven with bacterial arthritis (BA), eight with probable bacterial arthritis (PBA) and eight with osteoarthritis (OA) were studied using the immunoperoxidase staining technique. The oncoproteins studied were expressed both in the synovial lining layer and in the sublining layer, consisting of lymphocytes, other inflammatory cells and blood vessels. Among the six disease entities, RA and OA appeared to be the most distinct, whereas the results obtained for ReA and OSA, and on the other hand for BA and PBA, closely resembled each other. The expression of Myc, Myb, Fos and Jun was significantly correlated both to the degree of synovial hypercellularity and the synovial lymphocytic infiltration. For Ras, such a correlation could not be seen. We conclude that we find no evidence of a cell lineage-specific or a disease-specific abnormality of proto-oncogene products in RA, and the expression of these oncoproteins is consistent with inflammation rather than with any primary abnormality of cell growth.

Synovial fluid L-lactic acid in acute arthritis of the adult knee joint.

Determination of synovial fluid (SF) lactic acid has been suggested to be an unspecific indicator of SF leukocytosis, and it is not recommended for differential diagnosis of bacterial arthritis. We analyzed the L-lactic acid content by enzymatic UV-method in 65 SF samples obtained from adult patients with acute knee arthritides. The concentration of L-lactic acid was not high in any SFs with intensive leukocytosis. The mean concentration of L-lactic acid was 13.5 mmol/l (95% confidence intervals 9.4; 17.6 mmol/l) in the synovial-fluid samples from culture-positive arthritis and 5.5 mmol/l (4.9; 6.2 mmol/l) in the synovial-fluid samples from culture-negative arthritis. Determination of SF L-lactic acid is an important part of the diagnostic setup for acute arthritis. Values > 9 mmol/l strongly support occurrence of bacterial arthritis and indicates an immediate onset of the treatment.

Group II phospholipase A2 in synovial fluid and serum in acute arthritis.

Increased catalytic activity of synovial-type (group II) phospholipase A2 (syn-PLA2), has been associated with cartilage erosions in rheumatoid arthritis and osteoarthritis. The catalytic activity of phospholipase A2 and the concentration of syn-PLA2 were measured in a prospective study in synovial fluid (SF) samples from 66 patients with acute knee joint effusion. The median (range) of the concentration of syn-PLA2 in SF was 210 micrograms/l (80-1480 micrograms/l) in culture-positive septic arthritis, 460 micrograms/l (270-1040 micrograms/l) in reactive arthritis, 780 micrograms/l (120-2710 micrograms/l) in osteoarthritis and 230 micrograms/l (80-1400 micrograms/l) in traumatic joint effusions. High concentrations of syn-PLA2 are found also in SF of patients with arthritides not expected to lead to permanent destruction of cartilage.