Abstract
Macrophages are endowed with a variety of receptors for lineage-determining growth factors, T helper (Th) cell cytokines, and B cell, host, and microbial products. In tissues, macrophages mature and are activated in a dynamic response to combinations of these stimuli to acquire specialized functional phenotypes. As for the lymphocyte system, a dichotomy has been proposed for macrophage activation: classic vs. alternative, also M1 and M2, respectively. In view of recent research about macrophage functions and the increasing number of immune-relevant ligands, a revision of the model is needed. Here, we assess how cytokines and pathogen signals influence their functional phenotypes and the evidence for M1 and M2 functions and revisit a paradigm initially based on the role of a restricted set of selected ligands in the immune response.
Keywords
MacrophageImmune systemBiologyPhenotypeReceptorCell biologyImmunologyFunction (biology)Lineage (genetic)T cellGeneticsIn vitroGene
Affiliated Institutions
Related Publications
The Metabolic Signature of Macrophage Responses
Macrophages are a heterogeneous population of immune cells playing several and diverse functions in homeostatic and immune responses. The broad spectrum of macrophage functions ...
Macrophage plasticity, polarization, and function in health and disease
Macrophages are heterogeneous and their phenotype and functions are regulated by the surrounding micro‐environment. Macrophages commonly exist in two distinct subsets: 1) Classi...
Macrophage Polarization: Different Gene Signatures in M1(LPS+) vs. Classically and M2(LPS–) vs. Alternatively Activated Macrophages
Macrophages are found in tissues, body cavities, and mucosal surfaces. Most tissue macrophages are seeded in the early embryo before definitive hematopoiesis is established. Oth...
Diversity, Mechanisms, and Significance of Macrophage Plasticity
Macrophages are a diverse set of cells present in all body compartments. This diversity is imprinted by their ontogenetic origin (embryonal versus adult bone marrow–derived cell...
Macrophage Polarization States in the Tumor Microenvironment
The M1/M2 macrophage paradigm plays a key role in tumor progression. M1 macrophages are historically regarded as anti-tumor, while M2-polarized macrophages, commonly deemed tumo...
Publication Info
- Year
- 2014
- Type
- review
- Volume
- 6
- Pages
- 13-13
- Citations
- 4493
- Access
- Closed
External Links
Social Impact
Altmetric
PlumX Metrics
Social media, news, blog, policy document mentions
Citation Metrics
4493
OpenAlex
Cite This
Fernando O. Martínez,
Siamon Gordon
(2014).
The M1 and M2 paradigm of macrophage activation: time for reassessment.
F1000Prime Reports
, 6
, 13-13.
https://doi.org/10.12703/p6-13
Identifiers
- DOI
- 10.12703/p6-13