Interleukin-1 beta and interleukin-1 alpha stimulate the plasminogen activator activity and prostaglandin E2 levels of human synovial cells.

Monocyte-macrophage polypeptides (monokines) cause synovial cells to increase the levels of putative mediators of destruction and inflammation. This interaction may account for some of the properties of rheumatoid pannus. We report here that samples of purified human interleukin-1 beta (IL-1 beta) and recombinant IL-1 alpha stimulate both the plasminogen activator activity and prostaglandin E2 levels of human synovial fibroblast-like cells.

Interleukin-1 beta and interleukin-1 alpha stimulate the N-acetyl-beta-glucosaminidase activity of human synovial cells.

The properties of synovial cells are altered in vitro by monocyte-macrophage polypeptides (monokines), and these changes could explain some of the properties of the inflamed synovium in rheumatoid disease. Purified monokines have become available only recently for testing on the target synovial cells. We report here that purified human interleukin (IL)-1 beta and recombinant human IL-1 alpha stimulate the extracellular activity of the lysosomal hydrolase, N-acetyl-beta-glucosaminidase (NAG), of human synovial fibroblast-like cells.

Diverse morphological responses of normal human synovial fibroblasts to mononuclear leukocyte products: relationship to prostaglandin production and plasminogen activator activities, and comparison with the effects of purified interleukin 1.

Supernatant media from cultured human mononuclear blood leukocytes (MCCM) induced morphological changes in normal human synovial fibroblasts in culture, including the formation of cells with a dendritic or stellate morphology and, less frequently, cells with a striking fenestrated appearance. These changes were fully reversed within 1 h of removing the MCCM. They were inhibited by indomethacin, the glucocorticoids hydrocortisone, prednisolone and dexamethasone, and by colcemid, but not by actinomycin D and only weakly by cycloheximide.

Peripheral blood mononuclear cells stimulate N-acetyl-beta-glucosaminidase levels of human synovial fibroblast-like cells.

Fibroblast-like synovial cells isolated from intact joints of non-arthritic human donors released up to nine-times higher activity of the lysosomal acid hydrolase N-acetyl-beta-glucosaminidase (NAG) than controls when incubated in conditioned medium from homologous peripheral blood mononuclear cells (MCCM). This increase occurred without decrease in cell numbers or other evidence of cytotoxicity. An increase in cell-associated NAG activity was also suggested, but this was not statistically significant.