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. 2004 Nov 15;114(10):1389–1397. doi: 10.1172/JCI23595

Figure 3.

Figure 3

Potential mechanisms of conventional allergen immunotherapy. High-dose allergen exposure during immunotherapy results in both immune deviation of Th2 responses in favor of a Th0/Th1 response and in the generation of IL-10– and TGF-β–producing CD4+CD25+ T cells, possibly Tregs. IFN-γ–induced activation of bystander macrophages and/or other cells represents an alternative source of these inhibitory cytokines. During subsequent natural environmental exposure to allergens, the activation and/or maintenance of the usual atopic Th2 T cell response is inhibited. Additionally, these cytokines induce preferential switching of B cell responses in favor of IgG and IgG4 antibodies (and possibly IgA antibodies under the influence of TGF-β). IgG may also inhibit IgE-facilitated allergen binding to antigen-presenting cells with subsequent downregulation of IgE-dependent Th2 T lymphocyte responses. Blue arrows represent immune response pathway to natural exposure (low-doses Ag and IgE); green arrows represent immune response pathway to immunotherapy (high-dose Ag); red blocked lines represent inhibition (high-dose Ag); dotted lines represent possible means of action not yet proven.