The main effects of IL-13 are Inhibition of activation and cytokine secretion by macrophages Coactivation of B-cell proliferation Upregulation of class II MHC molecules and CD23 on B cells and monocytes Induction of switch to IgG1 and IgE Induction of vascular cell adhesion molecule 1 (VCAM-1) on endothelium Clinical relevance of IL-13 includes Involvement of IL-13 (with IL-4) in the production of IgE in atopic allergy IL-15 is produced by B cells, dendritic cells, macrophages, monocytes, NK cells, and T cells.