Medicine & USMLE


  1. TNF-alpha
  2. IL-1
  3. IL-2
  4. IL-3
  5. IL-4
  6. IL-5
  7. IL-6
  8. IL-8
  9. IL-10
  10. IL-12
  11. TGF-beta
  12. IFN-alpha and IFN-beta
  13. IFN-gamma


Interleukin-4 (IL-4) is a cytokine produced by Th2 cells. IL-4 also promotes proliferation of Th2 cells, creating a positive feedback loop. The final goal of IL-4 is to stimulate B-cells to produce Immunoglobulin E (IgE), which is critical in the immune response against parasitic worms, as well as in allergy and asthma.

Key Points

  • Interleukin-4 (IL-4)
    • Secreted by Th2 cells
      • Also by mast cells, to a lesser extent
    • Induces differentiation of Th2 cells
      • Works in autocrine fashion to amplify Th2 response
    • Enhances B cell growth and class switching to Immunoglobulin E (IgE)
      • Indirectly plays a role in allergy through IgE
      • Also enhances class switching to IgG, to a lesser extent