Tumor Necrosis Factor-α– and Interleukin-6–Triggered Mast Cell Development From Mouse Spleen Cells

Abstract

AbstractWe previously showed that interleukin-3 (IL-3) alone is not sufficient, although it is essential for murine mucosal-type mast cell development and that prostaglandin E (PGE) and interferon-γ (IFN-γ) are critical for survival or differentiation of mast cell precursors. We also confirmed that IL-4 is a key inhibitor for mast cell precursors despite being a growth factor of mast cells. In the present work, mouse spleen cells were cultured with recombinant (r) IL-1β, rIL-5, rIL-6, rIL-9, granulocyte-macrophage colony-stimulating factor (GM-CSF ), stem cell factor (SCF ), tumor transforming growth factor-β (TGF-β), or tumor necrosis factor-α (TNF-α) in the presence of endogenous IL-3. After 12 days of culture, mast cell development was induced by rIL-6 and rTNF-α. rIL-1β, rIL-5, rGM-CSF, rTGF-β and even the mast cell growth factors, rIL-9 and rSCF, failed to induce mast cell development. However, unlike IL-9 and SCF, IL-6 and TNF-α did not promote the growth of mast cells already developed. Macrophage may be one of the responsive cells of IL-6 and TNF-α in the cultures, because removal of macrophages greatly reduced the mast cell development induced by the cytokines. The actions of TNF-α and IL-6 were inhibited by indomethacin, an inhibitor for prostaglandin synthesis, and by neutralizing anti–IFN-γ and anti–IL-3 antibodies. rIL-4, when added at the start of the culture, also inhibited mast cell development induced by rIL-6 and rTNF-α. Nevertheless, neutralizing anti–IL-6 and anti–TNF-α antibodies did not suppress mast cell development induced by PGE and IFN-γ. TNF-α and IL-6 enhanced IFN-γ production, but suppressed IL-4 production in the cultures. Mast cell numbers induced were inversely and directly proportional to IL-4 and IFN-γ levels, respectively. These results indicate that inflammatory mediators as triggers are important for mast cell development, although they are not the mast cell growth factors.