Table 1.

M2 Macrophage phenotypes and their different stimuli, secreted cytokines, and functions.

M2 Phenotype	Stimulus	Secreted Cytokines	Function
M2a	IL-4, IL-13	TNF-α, IL-1α, IL-1 β, IL-6, IL-12, IL-23, CXCL9, CXCL10, CXCL11, CXCL16, CCL5, TGF-β, IGF-1	Increase endocytic activity, cell growth, and tissue repair
M2b	TLR ligands, IL-1 β	IL-1 β, TNF-α, IL-6, IL-10, CCL1	Regulate immune function by promoting Th2 differentiation
M2c	Glucocorticoids, IL-10, TGF-β	IL-10, TGF-β, CCL16, CCL18, CXCL13	Phagocytosis of apoptotic cells
M2d	TLR antagonists	IL-10, VEGF	Promote angiogenesis and tumor growth