Mast cell subpopulations in the synovial tissue of patients with osteoarthritis: selective increase in numbers of tryptase-positive, chymase-negative mast cells
✍ Scribed by Buckley, Mark G.; Gallagher, Patrick J.; Walls, Andrew F.
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 410 KB
- Volume
- 186
- Category
- Article
- ISSN
- 0022-3417
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✦ Synopsis
Although there is relatively little evidence of inflammation in osteoarthritis (OA), increases in mast cell numbers and mast cell activation are prominent features of the synovial tissue. As little is known of the types of mast cells which may be involved, the numbers and distribution of mast cell subpopulations have been investigated as defined according to their content of proteases. Tissue was obtained from patients with OA undergoing total knee replacement surgery (n=14) and from control subjects either post-mortem (n=11) or following leg amputation for peripheral vascular disease (n=3); a double-labelling immunocytochemical procedure with monoclonal antibodies specific for tryptase and chymase was applied to identify those mast cells which contain both tryptase and chymase (MC TC ) and those with tryptase but not chymase (MC T ). There was considerable variation between individual tissues and between sites of tissue sampling, but cells of the MC TC subset were predominant in the synovial layer of both groups of subjects without joint disease, accounting for some 60 per cent of all mast cells present. In tissue from OA patients, however, there appeared to have been a striking shift in the relative proportions of mast cells from the MC TC to the MC T phenotype, with many more MC T cells present in the synovial tissues of OA patients (median 53 MC T /mm 2 ) than in tissue from post-mortem (7•5 MC T /mm 2 , P<0•0001) or amputation controls (12 MC T /mm 2 ). In contrast, numbers of synovial MC TC cells in the synovium of OA patients (20 MC TC /mm 2 ) differed little from those in either of the control groups (both 12 MC TC /mm 2 ). In several other conditions, the MC T cells have been linked with inflammatory events, but it seems that in OA, other factors may be operating to induce a selective expansion of this subpopulation.