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T 2 model

T 2 helper cells lead to a humoral immune response, typically against extracellular parasites such as helminths. They are triggered by the polarising cytokines IL-4 and IL-2, and their effector cytokines are IL-4, IL-5, IL-9, IL-10, IL-13 and IL-25. The main effector cells are eosinophils, basophils, and mast cells as well as B cells, and IL-4/IL-5 CD4 T cells. The key T 2 transcription factors are STAT6 and GATA3. IL-4 is the positive feedback cytokine for T 2 cells differentiation. Besides, IL-4 stimulates B-cells to produce IgE antibodies, which in turn stimulate mast cells to release histamine, serotonin, and leukotriene to cause broncho-constriction, intestinal peristalsis, gastric fluid acidification to expel helminths. IL-5 from CD4 T cells will activate eosinophils to attack helminths. IL-10 suppresses T 1 cells differentiation and function of dendritic cells. T 2 overactivation against antigen will cause Type I hypersensitivity which is an allergic reaction mediated by IgE. Allergic rhinitis, atopic dermatitis, and asthma belong to this category of overactivation. In addition to expressing different cytokines, T 2 cells also differ from T 1 cells in their cell surface glycans (oligosaccharides), which makes them less susceptible to some inducers of cell death.