DEMONSTRATION OF DIFFERENTIAL-EFFECTS OF CYTOKINES ON MAST-CELLS DERIVED FROM MURINE BONE-MARROW AND PERIPHERAL-BLOOD MONONUCLEAR-CELLS

Mouse bone marrow (BM) was cultured in the presence of recombinant mouse (rm) interleukin-3 (IL-3), rmIL-4, rmIL-5, rmIL-7, purified mouse (m) IL-9, rmIL-lO, recombinant human (rh) macrophage-colony-stimulating factors (M-CSF), rm granulocyte-macrophage colony-stimulating factors (GMCSF), rm stem cell factor (SCF), rh interferon-alpha (IFN-alpha), rmIFN-gamma, and mNGF to determine which cytokine would give rise to mast cells in murine BM cultures. From a starting population of 1x10(7) cells, 1.55x10(7) mast cells developed within 14 days in cultures supplemented by rmIL-3. No mast cells were seen at day 14 when any of the other cytokines were present alone, except for rmSCF, which supported the growth of <0.01% of mast cells observed in IL-3-dependent BM cultures. When rmIL-4, -5, -7, -10, mIL-9, rhM-CSF, rmGM-CSE, rmSCF, rhIFN-alpha, gamma, or mNGF were added to BM cultures in the presence of rmIL-3, mast cell growth increased 200% with the addition of rmSCF, and 10% when rmIL-4 or IL-9 was added. However, the addition of rhM-CSF, rmGM-CSF, rmIFN-gamma, and mNGF decreased the number of mast cells. Mast cell number, as determined by metachromatic stains, generally approximated the number of Fc epsilon RI(+) cells as assessed by PACS analysis. Among the cytokines, only rmIL-4 and rmSCF were able to support the survival of mast cell progenitors in the absence of obvious mast cell proliferation, similarly to rmIL-3. Only rmSCF alone, or in combination with rmIL-3 or -4, supported the growth of mast cells from mouse peripheral blood mononuclear cells (PBMC) where the number of mast cell precursors was about 90 per 10(6) PBMC. With time, mouse BM cells cultured in rmIL-3 became more responsive to rmSCF. Taken together, these data demonstrate that IL-3 is a major early mast cell growth factor, that mast cells become more dependent on SCF with time, and that the effects of IL-3 and SCF are upregulated (IL-4) or downregulated (M-CSF, GM-CSF, IFN-gamma) by both growth factors and proinflammatory cytokines.