Fibroblast-Derived Factors Induce Different Mast Cell Characteristics in Human Myeloid Cell Lines and Peripheral Monocytes.

Mast cell differentiation markers were studied by culturing monocytic (U937, THP1) a promyelotic (HL60) and a human mast cell line (HMC1) and peripheral human blood monocytes with fibroblast supernatants and feeder layers. Mast cell differentiation occurred on the basis of metachromasia, chloroacetate esterase, expression of mast cell-specific antigens (APAAP) and production of tryptase in all cell types, but to varying degrees and not at all with a FcεRI marker in monocytic lines. Direct cellular contact is thus not necessary for induction of mast cell differentiation by fibroblasts.