Monocyte and macrophage differentiation: circulation inflammatory monocyte as biomarker for inflammatory diseases

Biomarker Research

Table 2 Markers and functions of MC subsets in human and mouse

Species	Subsets	Surface markers	% in MNC	Chemokine receptors	Functions
Human	Classical	CD14⁺⁺CD16^-	80-95	CCR2^highCX3CR1^low	Phagocytosis
	Intermediate	CD14⁺⁺CD16⁺	2-11	CCR2^midCX3CR1^highCCR5⁺	Pro-inflammatory
	Non-classical	CD14⁺CD16⁺⁺	2-8	CCR2^lowCX3CR1^high	Patrolling
Mouse	Ly6C^high (Ly6C⁺)	CD11b⁺CD115⁺Ly6C^high	40-45	CCR2^highCX3CR1^low	Phagocytosis & Pro-inflammatory
	Ly6C^middle (Ly6C⁺)	CD11b⁺CD115⁺Ly6C^middle	5-32	CCR2^highCX3CR1^low	Pro-inflammatory
	Ly6C^low (Ly6C^-)	CD11b⁺CD115 ⁺Ly6C^low	26-50	CCR2^lowCX3CR1^high	Patrolling; tissue repair

Human MCs are divided into three subsets based on the cell surface expression of CD14 and CD16. CD14⁺⁺CD16^- MCs, also called the classical MC, are the most prevalent MC subset in human blood and express high level of CCR2. The CD14⁺⁺CD16⁺ MCs are intermediate MC which contribute significantly to atherosclerosis. The CD14⁺ CD16⁺⁺ MCs are referred to as non-classical monocytes which perform a in vivo patrolling function. Mouse MCs are divided into two subsets based on their cell surface expression of Ly6C. The Ly6C^high and Ly6C^middle subsets perform pro-inflammatory functions and express high level of CCR2, which is considered the counterpart of human classical MCs. The Ly6C^low subsets express low level of CCR 2, majorly patrol along the vascular endothelium and are involved in tissue repair, functionally similar to human non-classical MCs. CD, cluster of differentiation; CCR 2, chemokine (C-C motif) receptor 2; CX3CR1, CX3C chemokine receptor 1; Ly6C, lymphocyte antigen 6 complex.

ISSN: 2050-7771