Primate Monocytes - CD14, CD16 - Ziegler-Heitbrock

Macrophage development and polarization in chronic inflammation

Abstract

The mononuclear phagocyte system consists of monocytes, macrophages and dendritic cells. The main functions of monocyte and macrophages include chemotaxis, phagocytosis, endocytosis, secretion of factors that modulate inflammatory responses and microbial killing; all of which are integral to homeostasis, immune defence and tissue repair [1]. In humans, monocytes were initially defined on the basis of morphology (size and density) as well as intracellular monocyte-specific esterase, for instance. Expression level of CD64 (Fc!RI) was used for some time where CD64+ cells were larger and more phagocytic than smaller CD64− cells, which preferentially expressed MHC-I/II and secreted type 1 interferons. Nowadays, flow cytometry using anti-CD14 (directed to the LPS-binding domain) and CD16 (Fc!RIII-binding domain) antibodies has given three classifications namely, CD14++/CD16− (classical), CD14++/CD16+ (intermediate) and CD14low/CD16++ (non-classical)