Expression of c-kit by mesenteric lymph node cells from Nippostrongylus brasiliensis-infected mice and by mast cell colonies developing from these cells in response to 3T3 fibroblast-conditioned medium.

Mast cell committed progenitors are nongranulated cells found in mesenteric lymph nodes of mice infected with Nippostrongylus brasiliensis (Nb-MLN) but not from normal mice. Mast cell committed progenitors can respond to either IL-3 or to a factor(s) present in 3T3 fibroblast conditioned media (F-CM) by formation of mast cell colonies. Previous studies from ours and other laboratories suggested that mast cell differentiation involved the W allele product, c-kit, as a receptor and Sl allele product, stem cell factor, as a growth factor. We report here that Nb-MLN cells, which can respond to F-CM by mast cell colony formation, also contain cells that express message for c-kit, and that c-kit message cannot be detected in naive mesenteric lymph node cells, which cannot respond to F-CM. Antisense oligonucleotides to c-kit inhibit mast cell colony formation by Nb-MLN cells in response to F-CM, but not to conditioned medium of PWM-stimulated spleen cells as a source of IL-3. The antisense oligonucleotides also inhibit the degree of granulation by mast cells derived from culture. The results suggest that c-kit and its ligand, stem cell factor, are necessary for mast cell-committed progenitors to proliferate and granulate in response to F-CM but not IL-3.