ANALYSTS OF CELL-TYPES AND MEDIATOR PRODUCTION FROM TISSUES AROUND LOOSENING JOINT IMPLANTS

Quantitative immunophenotypic analysis of cell types present in peri-p rosthetic tissue [pseudosynovial membrane (PSM)] from aseptically loos e joint implants revealed considerable heterogeneity between tissues f rom different individuals. The monocyte/macrophage was the commonest l eucocyte type; however, its proportion varied widely. T cells normally accounted for similar to 5% of cells, but in a few cases formed >20% of cells. In all cases, there was a high ratio of CD4 to CD8 cells. PS M leucocytes were activated in most PSMs as judged by surface expressi on of CD23, CD25 and CD71. Analysis of the proportions of cell types i n PSM, OA synovium and RA synovium revealed similarities between the d ifferent tissue types. The levels of IL-1, IL-6 and prostaglandin E pr oduced by the PSM were correlated, but only IL-1 and IL-6 levels corre lated with markers of the monocyte/macrophage lineage. This result sug gests that prostaglandin E is produced in vivo by many PSM cell types.