Background The combination of recombinant human stem cell factor (rhSCF), r
h interleukin (IL)-6 and rhIL-10 was reported to be optimal for mast cell d
evelopment from cord blood progenitors and to induce chymase expression in
all such mast cells earlier in their development than tryptase.
Objective The effects of rhIL-6 and rhIL-10 in various combinations on the
rhSCF-dependent development of human mast cells from fetal liver progenitor
s were examined in serum-free media.
Methods Dispersed fetal liver cells were cultured in serum-free AIM-V mediu
m with rhSCF alone, or with combinations of rhIL-6 and rhIL-10. Tryptase an
d chymase expression, surface Kit expression, metachromasia with toluidine
blue and apoptosis were measured.
Results Neither rhIL-6 nor rhIL-10 nor the two interleukins together, when
included from day 0 of culture, affected the number or protease phenotype o
f mast cells at 1 or 3 weeks. Expression of tryptase paralleled the appeara
nce of metachromasia and surface Kit, both of which preceded chymase expres
sion, regardless whether a rabbit polyclonal or mouse monoclonal anti-chyma
se antibody preparation was used. On the other hand, rhIL-6 markedly attenu
ated baseline levels of apoptosis in the presence of rhSCF as well as apopt
osis occurring after withdrawal of rhSCF, whereas rhIL-10 had no effect.
Conclusion RhIL-6 protected fetal liver-derived mast cells from apoptosis,
particularly after withdrawal of rhSCF, but neither rhIL-6 nor rhIL-10 nor
the combination of these interleukins affected the numbers or protease phen
otype of these mast cells.