Conditioned media obtained from a human mastocytosis cell strain induce mast cells expressing chymase but not tryptase from human progenitors.

Human mast cells (MC) were derived from umbilical cord blood and bone marrow progenitors cultured in the presence of a conditioned medium from a human mastocytosis cell strain and recombinant human kit ligand (rhKL). KL induced MC of predominantly two immunophenotypes, MC(T) and MC(TC). In contrast, the conditioned medium induced MC subtypes MC(TC) and a third subtype, MC(C), positive for chymase but negative for tryptase. This study clearly demonstrates that a third type of MC, MC(C), can be induced in vitro from normal human progenitors.