Enhanced release of von Willebrand factor by human endothelial cells in culture in the presence of phorbol myristate acetate and interleukin 1.

Human umbilical vein endothelial cells (EC) were cultured in the presence of 4 beta-phorbol 12-myristate 13-acetate (PMA), interleukin 1 (IL-1) and interleukin 2 (IL-2), and secretion of von Willebrand factor activity (vWF, Ristocetin Co-factor) and von Willebrand factor antigen (vWFAg) measured at intervals. The levels of both vWF and vWFAg in cultures containing IL-1 were significantly higher than those in control cultures after longer than 5-6 days growth. Similarly, the levels of vWF and vWFAg were significantly increased in cultures containing PMA, but in these instances the rate of cell growth appeared to be enhanced, and confluence was observed after 6 days compared to 9-10 days in control cultures. vWF and vWFAg also increased significantly in the supernatant of confluent control EC incubated further with IL-1. Moreover, the immuno-fluorescence pattern of vWFAg in these treated cells was markedly less granular than that of control cells. Immuno-fluorescence of PMA-treated cells suggested that vWFAg might be less granular than in control EC but the mean levels of vWF and vWFAg in the supernatant of cells incubated with PMA were not significantly different from control values. The results of all assays in the presence of IL-2 were not significantly different from those of control cells. In all instances no morphological evidence of endothelial injury was observed, and more than 90% of cells remained viable at the termination of cultures. The results indicated that the synthesis and release of vWF were increased in the presence of PMA, and secretion of vWF was stimulated by IL-1.(ABSTRACT TRUNCATED AT 250 WORDS)