The influence of synovial fibroblasts on the phagocytosis of Staphylococcus by polymorphonuclear cells.

It has been suggested that the reduced resistance of patients with rheumatoid arthritis (RA) to bacterial joint infections may be due in part to polymorphonuclear cell (PMN) function. To obtain further insight into the mechanism that contribute to the increased susceptibility of RA patients to such infections we investigated the influence of different solid surfaces on the ingestion of various bacterial strains by PMN. Both in the presence and absence of serum, phagocytosis of bacteria by PMN was significantly lower on monolayers of synovial fibroblasts as compared to monolayers of endothelial cells and embryonic fibroblasts. It could be shown that the relative influence of the solid surface on the results of the phagocytosis assay increased when decreasing concentrations of purified IgG were used. The results of this study suggested that the effect of synovial fibroblasts on PMN may lead to reduced clearance of bacteria from the joint.