Cholera toxin enhances factor-dependent colony growth of murine mast cell progenitors

Mast cell colonies were observed when mouse spleen or bone marrow cells were cultured in the presence of medium conditioned by concanavalin-A-stimulated spleen cells, indicating that the medium contains the factor(s) necessary for the formation of these colonies. This factor-dependent colony growth of mast cell progenitors was enhanced by cholera toxin and prostaglandin E, which act on cellular growth mainly by elevating the intracellular cyclic-AMP level. The effect of the toxin was neutralized by preincubation of the toxin with GM1 ganglioside, the receptor substance for cholera toxin, suggesting that cholera toxin exerts its action through GM1 gangliosides present on mast cell progenitors. The toxin B subunit, which binds to GM1 ganglioside but does not elevate intracellular cyclic AMP level, did not affect the colony growth of mast cell progenitors. From these results, it is suggested that intracellular cyclic AMP levels may be involved in colony growth of mast cell progenitors.