Enhancement by interleukin-1 (IL-1) of plasminogen activator inhibitor (PA-I) activity in cultured human endothelial cells

Summary Cultured human endothelial cells produce increased levels of PA-I when stimulated with IL-1. The stimulatory effect was elicited by both alfa (pI 5) and beta (pI 7) IL-1 molecules. The effect was both dose and time-dependent, plateau reached after 8 h. The PA-I measured in cell extracts was SDS-resistant with an apparent m.w. of 53 Kd and inhibited both tissue-type plasminogen activator (t-PA) and urokinase (UK). No change in t-PA antigen level was detected with any of the IL-1 preparations tested.