It is widely known that mast cells and cytokine TNF-a are both involved in inflammatory reactions. Therefore, we have studied whether TNF-c! can cause histamine secretion from human adenoidal and cutaneous mast cells. The experiments were performed in vitro on mast cells isolated from tissues by enzymatic dispersion technique. The results of our experiments have clearly shown that this cytokine stimulates mast cells to histamine release. TNF-alpha-induced histamine release was concentration-and time-dependent. Moreover, the release of histamine evoked by TNF-alpha was also dependent on reaction temperature and on glycolytic and oxidative cellular metabolism. We have concluded that TNF-alpha is a potent stimulus for mast cells to release histamine and that it induces histamine release via an active, secretory process. (C) 1997 Elsevier Science B.V.