CC-Chemokine CCL15 Expression and Possible Implications for the Pathogenesis of IgE-Related Severe Asthma

Figure 2

CD4+ Th subsets in asthma and the potential role of CCL15 production by ASMC. Mixed Th1 cells produce both Th1 and Th2 cytokines (IFN-γ, IL-3, IL-9, IL-13, GM-CSF) when stimulated by exposure to an antigen plus IL-18. Th2 and Th17 cells secrete TNF-α, while Th9 cells are differentiated from Th2 cells secrete IL-9, which promotes IgE production by B cells and the production of IL-8, CCL11, and prostaglandin E₂ (PGE₂) by ASMC. IgE promotes the inflammatory phenotype of ASMC, and these cells produce CCL15 when stimulated with both TNF-α and IFN-γ. IL-21 from Th17 cells has been suggested to regulate IgE production by B cells, and Tregs have an inhibitory effect on it.