Nerve growth factor-beta induces mast-cell marker expression during in vitro culture of human umbilical cord blood cells

Nerve growth factor-beta (NGF) is known as a growth factor for human basophils and murine mast cells and has recently been shown to also up-regulate mast cell characteristics in human leukaemic mast cells. We have examined here the effect of NGF on the differentiation of normal human mast cells from cord blood progenitors during culture with stem cell factor (SCF), NGF alone or in combination, or fibroblast supernatants. All these supplements induced mast cell immunoreactivity against tryptase, c-Kit and Fc epsilon RI alpha, but none of the cells reacted against the basophil specific antibody 2D7 before or during culture. Intracellular tryptase activity increased as well, with maximal levels on combined culture with SCF and NGF. On reverse transcription-polymerase chain reaction (RT-PCR), cells lacked tryptase and chymase and expressed low levels of Fc epsilon RI and c-Kit mRNA prior to culture, with marked up-regulation of Fc epsilon RI and c-Kit, and with de novo expression of mast-cell specific alpha- and beta-tryptase by week 3, and of chymase by week 5. Only the TrkA and not the p75 NGF receptor was detected at m-RNA and protein level, and only the TrkA NGF receptor was up-regulated during NGF-driven culture. These findings show therefore that, like SCF, NGF is another growth factor that can induce and regulate human mast-cell development and differentiation.