Cellular effects of human leukocyte hydrolases III: inflammatory exudate and synovial fibroblasts.

Experiments were undertaken to determine whether lysosomal enzymes obtained from human polymorphonuclear leukocytes (PMN) might adversely affect the viability of human synovial fibroblasts. The effects of the PMN granule enzymes were additionally determined in the presence of an inflammatory exudate. These in vitro results indicated that as a result of these experimental conditions, the lysosomal enzymes, although present in relatively high concentration, were incapable of cell destruction and could only release cells from their growth surfaces; as could other proteases. However, even this effect was not expressed in the presence of naturally occurring inhibitors widely distributed in body fluids, such as serum; and most importantly which are also present in inflammatory exudates. This was in spite of the relatively high dilution of serum and inflammatory exudate used. So that, in effect, the relatively dilute inhibitors present in both serum and inflammatory exudates prevented the relatively concentrated lysosomal enzymes from exerting any discernible effects on either the cells, or the intercellular substance under these experimental conditions. This possibly suggests that the role of PMN granule enzymes as mediators of the cellular destruction observed in many inflammatory diseases, needs further elucidation.