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. The morphological responses to MCCM could be reproduced by MCCM fractions containing interleukin 1-like activity and by purified forms of human interleukin 1 (IL-1), including monocyte-derived IL-1 beta and recombinant IL-1 alpha. These responses were also inhibited by indomethacin, indicating a link with prostanoid production. However, the morphological responses were not related to the stimulation of plasminogen activator activity due to MCCM, MCCM fractions, or IL-1.