Macrophage (M1 Phenotype) (M1 Macrophage)

M1 macrophages, or classically activated macrophages, are a polarized state of macrophages characterized by their pro-inflammatory and microbicidal functions. They are induced by IFN-γ, LPS, and other stimuli, leading to the production of pro-inflammatory cytokines, enhanced antigen presentation, and potent microbicidal activity through NO and ROS. While essential for host defense, excessive or prolonged M1 activation can contribute to tissue damage and chronic inflammatory conditions.

Other names

Classically Activated MacrophageM1 Polarized Macrophage

M1 macrophages are induced by IFN-γ, LPS, GM-CSF, or PAMPs, leading to activation of transcription factors like IRF5, NF-κB, and STAT1. This results in the production of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α, IL-12, IL-23), increased expression of MHC-II and costimulatory molecules (CD80/CD86), and enhanced microbicidal activity through NO and ROS production.