Table 1.

M2 macrophage subtypes and their characteristics.

Phenotype	Stimulating factors	Surface markers	Key secreted molecules	Biological roles	Ref.
M2a	IL-4, IL-13	CD206, CD209, Dectin-1, MHC-II	IL-10, TGF-β, PDGF, IGF, Arg-1, Fizz1, Ym1, CCL17, CCL18, CCL22	induce Th2 response, tissue repair, monocyte recruitment	(27, 29–31; 32)
M2b	Immune complexes + LPS	CD86, MHC-II	IL-10, TNF-α, IL-1β, CCL1	induce Th2 response, mediate pro- and anti-inflammatory response	(33–35)
M2c	IL-10, TGF-β, glucocorticoids, PGE2	CD163, CD206, MerTK	IL-10, TGF-β, Arg-1	promote immunosuppression and clearance of debris	(36–39)
M2d	IL-6, A2R-agonists, TLR-agonists, LPS	CD163	VEGF, IL-10, IL-6, M-CSF, iNOS, CCL2	support tumor progression and angiogenesis	(27, 40–42)