Monocyte and macrophage

Monocytes and macrophages are key immune cell types of the mononuclear phagocyte system, arising from myeloid progenitors in the bone marrow. Monocytes circulate briefly in blood and differentiate into macrophages in tissues, where they serve as professional phagocytes, clearing pathogens and dead cells, orchestrating inflammation, presenting antigens to lymphocytes, producing cytokines, and maintaining tissue homeostasis. These cells show remarkable plasticity in function and phenotype depending on environmental cues and tissue type. They are centrally involved in the development and regulation of infectious, autoimmune, cardiovascular, and malignant diseases. As a result, strategies to target monocytes or macrophages—either by inhibiting their recruitment, depleting subpopulations, or modulating their immunoregulatory functions—constitute an active area of therapeutic development, though specificity and systemic safety concerns remain unresolved challenges.

Other names

MonocyteMacrophageMononuclear phagocyte (system)Monocytes/macrophagesMo/Mφ

Drugs targeting monocytes and macrophages typically act via inhibition of recruitment (e.g., CCR2/CCR5 antagonists); modulation of polarization (shifting M1/M2 phenotypes); inhibition of cytokine signaling (e.g., anti-TNF, anti-IL-6); depletion (e.g., CSF-1R inhibition); or immune checkpoint blockade (modifying macrophage antigen presentation).