Th9 cells are a novel subset of Th cells that develop independently of Th1, Th2, Th17, and Treg cells. Th9 cells are characterized by the secretion of IL-9. However, in contrast to murine Th9 cells, IL-10 is not expressed by human Th9 cells. Naïve CD4+ T cells can be differentiated into Th9 cells with the combination of TGFβ and IL-4. In this differentiation model, IL-4 suppresses TGFβ-induced Foxp3 expression, while IL-4 mediates the upregulation of GATA3. While the cytokines IL-1β, IL-6, IL-10, IL-21, IFNα, and IFNβ enhance IL-9 expression of cultured Th9 cells, IFNγ and IL-27 inhibit its production in human Th9 cells; making it possible that Th1 response may suppress Th9 cell differentiation. Th9 cells do not express many of the other Th cell associated cytokines such as IFNγ (Th1), IL-4, IL-5, and IL-13 (Th2), or IL-17 (Th17), nor do they express the master regulators of the other Th cell types T-bet (Th1), RORγt (Th17), or Foxp3 (Treg), with the exception of GATA3 (Th2).

Relevant Recombinant Proteins

  • TGF-beta
    • Essential to the reprogramming of Th0 cells into mature Th9 cells
  • IL-4
    • Blocks the generation of TGFβ-induced Foxp3+ Treg cells and induces Th9 cell formation
  • IL-6, IL-10, IL-21 and IFN-alpha
    • Enhance IL-9 expression of cultured Th9 cells:

Relevant Neutralizing Antibodies

  • Anti- IFN-gamma
    • Prevents inhibition of IL-9 production in Th9 cells.
  • Anti- IL-27
    • Prevents inhibition of IL-9 product in Th9 cells. (Since IL-27 is largely made by DC and macrophages, neither of which is present in purified naïve T-cell culture, anti-IL27 should only be used for in vivo studies)