Regulation of eosinophil-active cytokine production from human cord blood-derived mast cells

Human mast cells are multifunctional tissue-dwelling cells that play a crucial role in eosinophil-dependent disorders, such as asthma and parasitic diseases, by the secretion of eosinophil-active mediators. Mast cell-derived cytokines, generated in response to cross-linking of the high-affinity IgE receptor, can regulate eosinophil activation, survival, and chemotaxis. In this study, mast cells generated from human cord blood progenitors (stem cells) were studied for eosinophil-active inflammatory cytokine expression. Cord blood-derived mast cells (CBDMC) expressed typical intracellular scroll granules and microvilli-like structures on their cell surfaces, demonstrated the presence of tryptase, and elaborated prostaglandin D₂ (PGD₂) after cross-linkage of the high-affinity receptor for IgE (FcεRI). CBDMC expressed tumor necrosis factor-α (TNF-α) and the eosinophil-active growth factors, interleukin-5 (IL-5) and granulocyte-macrophage colony-stimulating factor (GM-CSF) after activation. (IL-1β greatly enhanced IgE-dependent production of these cytokines in response to FcεRI cross-linkage, suggesting a role for bystander/phagocytic cells in modulating mast cell function. In contrast, interferon-α (IFN-α) inhibited IL-5 and GM-CSF generation, and the glucocorticoid, dexamethasone (Dex), inhibited production of IL-5 and GM-CSF from CBDMC. A macrophage-mast cell-eosinophil axis may existin vivo that may be susceptible to pharmacologic manipulation.