Effect of the c-kit Ligand on Mediator Release by Human Lung Mast Cells

IgE-independent mediator release or modulation of mediator release by cytokines has not been described for human lung mast cells (MC) so far. We recently showed that among a large number of cytokines examined the c-kit ligand (KL) is a unique cytokine capable of modulating histamine and leukotriene release in human lung mast cells. KL increases the IgE-dependent mediator release 2- to 3-fold without inducing substantial mediator release over the control by itself in freshly isolated cells. By contrast, this study shows that KL becomes a potent triggering agent per se in MC cultured for a few days without addition of KL or feeder cells. Furthermore, the IgE-dependent response is strongly enhanced after culture. The present study indicates that human and rodent MC differ strongly in their functional repsonsiveness towards cytokines, and that KL may be an important regulator of mast cell-associated disease, such as asthma.