Th2 Cells

Summary

T-Helper Type 2 (Th2) cells are a type of effector Helper T-cell with a variety of functions. Th2 cell differentiation and proliferation from naive Helper T-cells is induced by interleukin-4 (IL-4). Once activated, Th2 cells produce more IL-4, Interleukin-5 (IL-5), and Interleukin-10 (IL-10). IL-4 works in an autocrine fashion to stimulate the production of more Th2 cells, but it can also stimulate the production of IgE by B-cells. IL-5 works downstream to stimulate the production of IgA by B-cells, and also stimulates the proliferation and activation of eosinophils. IL-10 works to taper off the immune response to prevent collateral damage to normal tissue. Altogether, Th2 are effector T-cells, and their signalling products play important roles in parasite defense, mucosal immunity, and the shutting off of immune responses to prevent autoimmunity.

Key Points

• T-Helper Type 2 (Th2) Cell
  • Subtype of effector Helper T-cell in adaptive immune system
  • Coordinate humoral immunity against specific antigens (e.g. parasites)
  • Induced by Interleukin-4 (IL-4)
    • Also by Interleukin-2 (IL-2), but IL-2 is nonspecific (stimulates all lymphocytes)
    • IL-4 released by certain antigen presenting cells (e.g. mast cells) and Th2 cells (self-promoting)
    • Inhibited by IFN-gamma and IL-12 (cytokines mediating Th1 differentiation)
  • Secretes
    • Interleukin-4 (IL-4)
      • Promotes Th2 differentiation in self-promoting manner
      • Stimulates production of Immunoglobulin E (IgE) by B cells
    • Interleukin-5 (IL-5)
      • Activates Eosinophils
      • Stimulates production of Immunoglobulin A (IgA) by B cells
    • Interleukin-10 (IL-10)
      • anti-inflammatory function
    • Also produces Interleukin-13 (IL-13) 
      • Signals with IL-4 to preferentially promote B-cell lgE production