Table 1.

Nomenclature of activated macrophages/microglia

Classic nomenclature	Novel nomenclature	Activating molecules	Notes	Citations
M0/Unpolarized	M(-)	None, M-CSF, or GM-CSF	M-CSF or GM-CSF may be used to compare with macrophages	Durafourt et al., 2012
M1	M(LPS)	LPS, IFNγ or both	a.k.a. Classical activation	Mantovani et al., 2004
	M(IFNγ)
	M(LPS + IFNγ)
M2	M(IL4)	IL4	a.k.a. Alternative activation	Stein et al., 1992; Gordon, 2003; Sierra-Filardi et al., 2010
M2a	M(IL4 + IL13)	IL4 and IL13	Profile associated with anti-inflammatory phenotype in macrophages	Taylor et al., 2005; Leidi et al., 2009
M2b	M(Ig + LPS)	Immune complexes and LPS	Profile associated with pro-inflammatory cell-surface protein expression but IL10 secretion in macrophages	Edwards et al., 2006; Leidi et al., 2009
M2c	M(IL10 + TGFβ1)	IL10 and TGFβ1	Profile associated with tissue remodelling and immune suppression in macrophages	Mantovani et al., 2004; Leidi et al., 2009

GM-CSF = granulocyte-macrophage colony stimulating factor, now known as CSF2; M-CSF = macrophage colony stimulating factor, now known as CSF1.