Table 3.
Overview of the main functions of M1 and M2 associated markers
| General macrophage markers | ||
|---|---|---|
| CD11b |
Cluster of differentiation 11b |
Expressed on all myeloid lineage cells |
| F4/80 (EMR1) |
EGF-like module-containing mucin-like hormone receptor-like 1 |
Expressed on most tissue macrophages |
| Iba1 |
Ionized calcium binding adaptor molecule 1 |
Expressed on macrophages (and microglia) |
|
M1 associated markers | ||
| IFNγ |
Interferon gamma |
Polarize macrophages towards M1; critical for innate and adaptive immunity against viral and intracellular bacterial infections (also produced by macrophages) [40] |
| IL-12p40 |
Interleukin 12 subunit p40 |
Pro-inflammatory cytokine; induces Th1[41], production of cytokines (mainly IFNγ) [42], stimulation cell-mediated immunity against microbial pathogens [43] |
| iNOS |
Inducible nitric oxide synthase |
Production of nitric oxide (NO) using arginine as a substrate; defense against microorganisms [44] |
|
M2 associated markers | ||
| Arg1 |
Arginase 1 |
Production of L-ornithine and urea using arginine as a substrate, first step to production of polyamines (growth factors in the nervous system) [45]; counteracts iNOS |
| CDH1 |
Cadherin-1 |
Cell-cell adhesion [46], interaction with CD103 of regulatory T-cells [47] |
| Clec7a (dectin1) |
C-type lectin domain family 7, member a |
Pattern recognition; non-opsonic beta-glucan receptor [48] |
| FIZZ1 |
Found in inflammatory zone |
Lipid and sugar metabolism; angiogenesis-promoting factor [49] |
| IL-4 |
Interleukin 4 |
Th2 effector cytokine: polarize macrophages to M2 [50]; IgE class switching, differentiation of CD4+ T-cells into Th2 cells [51] |
| IL-10 |
Interleukin 10 |
Anti-inflammatory cytokine [52] |
| IL-13 |
Interleukin 13 |
Th2 effector cytokine: polarize macrophages to M2; fibrosis; defense against parasite infections [53] |
| MRC1 |
Mannose receptor type C1 |
Pattern recognition, type II response promoting effect [54] |
| Rage |
Receptor for advanced glycosylation end products |
Pattern recognition; binds endogenous ligands such as S100B to stimulate trophic effects on neurons [55] |
| Trem2 |
Triggering receptor expressed on myeloid cells 2 |
Pattern recognition [56]; augmentation of apoptotic neuron phagocytosis and attenuation of proinflammatory cytokine secretion [57] |
| Ym1 (CH3L3) | Chitinase 3-like-3 | Weak eosinophils chemoattractant properties [58]; binds heparan sulfate, heparin, GlcN olimers; Th2 promoting effect [59] |