IL9 and autoimmune disease: Further characterization revealed that, depending upon the microenvironment, TH1 populations might engender a TH17 subpopulation, whose cytokine profile (e.g., IL17-A, IL-17 F, TNF-α, IL22, IL23, and IL9 in low concentrations) lends to a state of sustained T cell-driven inflammation seen in in autoimmune diseases and allergic reaction, or TH2 cells may generate TH9 subpopulations characterized by elevated levels of IL9 and IL10.