MAST-CELLS IN OSTEOARTHRITIC AND RHEUMATOID ARTHRITIC SYNOVIAL TISSUES OF THE HUMAN KNEE

The distribution and density of mast cells in the normal and diseased synovial membranes were investigated. The mast cell count (MCC) in the osteoarthritic (OA) synovium (36.9 +/- 26.9 cells/mm(2)) was signific antly higher than that in the rheumatoid arthritic (RA) synovium (18 /- 12.3 cells/mm(2)). There was a marked positive correlation between the MCC and the volume of joint fluid in OA (r = 0.544). There was a m arked negative correlation between the MCC and the volume of joint flu id in RA (r = -0.478). The synovial inflammatory score had a poor corr elation with the MCC in OA (r = 0.377) and RA (r = 0.305). No correlat ion was noted between MCC and age, sex, roentgenographic grades, disea se duration, C-reactive protein or leucocyte number in synovial fluid. Our data suggests, thus, that mast cells could be involved in the pat hogenesis of inflammatory diseases of the synovium, especially in the mechanism of hydroarthrosis.