| | Macrophage phenotype | Stimulants | Biomarkers | Secretions | Functions | Ref. |
| | M1 (classically activated macrophages) | IFN-γ, LPS, TNF-α, GM-CSF | CD86, CD40, CD38, NF-κB, STAT1 | TNF-α, IL-1α, IL-12, IL-23, IL-1β, IL-6, ROS, and RNS | Promote Th1 immune response, promote inflammatory response, fight pathogens, and inhibit the occurrence and development of tumors | [7, 8, 42–45] | | M2a (wound healing macrophages) | IL-4, IL-13, M-CSF | CD206, IL-1R, CCL17, Fizz1, STAT6 | TGF-β, IL-10, insulin-like growth factor (IGF), and fibronectin | Promote tissue repair and remodeling, promote fibrosis, and promote type II immune response by enhancing polyamines, collagen synthesis | [45, 53–56] | | M2b (regulatory macrophages) | Immune complex, TLR agonist, IL-1R agonist | IL-10, CCL1, LIGHT, CD86, SPHK1, TNF-α, IL-6, ERK, AP-1 | Proinflamatory cytokines (IL-1β, IL-6, and TNF-α), anti-inflammatory cytokine (IL-10 and low levels of IL-12) | Involve in proinflammatory and anti-inflammatory responses, immunomodulation, and Th2 activation | [45, 54–58] | | M2c (acquired inactivated macrophages) | Glucocorticoids, TGF-β, IL-10 | CD163, Mer receptor tyrosine kinase (MerTK), STAT3 | IL-10, TGF-β | Immune tolerance and tissue repair, suppress inflammation, promote phagocytosis and cholesterol efflux | [45, 55, 56, 58, 59] | | M2d (tumor-associated macrophages | TLR, adenosine A2A receptor
γ, IL-6 | Vascular endothelial growth factor A (VEGF-A), HIF-1α | Proteolytic enzymes (MMP-2), growth factors (VEGF), and anti-inflammatory mediators (TGF-β) | Beneficial for angiogenesis and tumor metastasis | [45, 55, 56, 60–64] |
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