Table 1

Summary of effects of cytokines

Important cellular and mediator effects
Lymphokines
IL-2• Eosinophilia in vivo
• Growth and differentiation of T cells
 IL-3• Eosinophilia in vivo
• Pluripotential haematopoietic factor
 IL-4• Eosinophil growth ↑
• Th2 cells ↑; Th1 cells ↓
• IgE ↑
 IL-5• Eosinophil maturation
• Apoptosis ↓
• Th2 cells ↑
• BHR
 IL-13• Activates eosinophils
• Apoptosis ↓
• IgE ↑
 IL-15• As for IL-2
• Growth and differentiation of T cells
 IL-16• Eosinophil migration
• Growth factor and chemotaxis of T cells (CD4+)
 IL-17• T cell proliferation
• Activates epithelia, endothelial cells, fibroblasts
Pro-inflammatory
IL-1• Adhesion to vascular endothelium ↑; eosinophil accumulation in vivo
• Growth factor for Th2 cells
• B cell growth factor; neutrophil chemoattractant; T cell and epithelial activation
• BHR
 TNF-α • Activates epithelium, endothelium, antigen presenting cells, monocytes/macrophages
• BHR
 IL-6• T cell growth factor
• B cell growth factor
• IgE ↑
 IL-11• B cell growth factor
• Activates fibroblast
• BHR
 GM-CSF• Eosinophil apoptosis and activation; induces release of leukotrienes
• Proliferation and maturation of haematopoietic cells; endothelial cell migration
• BHR
 SCF• VCAM-1 on eosinophils ↑
• Growth factor for mast cells
Inhibitory cytokines
IL-10• Eosinophil survival ↓
• Th1 and Th2 cells ↓
• Monocyte/macrophage activation ↓; B cells ↑; mast cell growth ↑
• BHR ↓
 IL-1ra• Th2 proliferation ↓
• BHR ↓
 IFN-γ• Eosinophil influx after allergen ↓
• Th2 cells ↓
• Activates endothelial cells, epithelial cells, alveolar macrophages/monocytes
• IgE ↓
• BHR ↓
 IL-18• via IFN-γ release ↓
• Releases IFN-γ from Th1 cells
• Activates NK cells, monocytes
• IgE ↓
Growth factors
PDGF• Fibroblast and airway smooth muscle proliferation
• Release of collagen
 TGF-β• T cell proliferation ↓
• Blocks IL-2 effects
• Fibroblast proliferation
• Chemoattractant for monocytes, fibroblasts, mast cells
• ASM proliferation ↓
  • IL = interleukin; TNF = tumour necrosis factor; GM-CSF = granulocyte-macrophage colony stimulating factor; SCF = stem cell factor; IFN = interferon; PDGF = platelet derived growth factor; NK = natural killer; Th cells = T helper cells; BHR = bronchial hyperresponsiveness; VCAM = vascular adhesion molecule; ASM = airway smooth muscle.