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Updated: Dec 29, 2025
Macrophage Differentiation and Polarization into an M2-Like Phenotype using a Human Monocyte-Like THP-1 Leukemia Cell Line
Published on: August 2, 2021
Standardized protocols for differentiation of THP-1 cells to macrophages with distinct M(IFNγ+LPS), M(IL-4) and
E W Baxter1, A E Graham2, N A Re2
1Leeds Institute of Cardiovascular and Metabolic Medicine, School of Medicine, University of Leeds, Leeds, UK; NIHR Biomedical Research Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK.
Abstract:
In vitro models of differing macrophage functions are useful since human monocyte-derived macrophages are short-lived, finite and vary from donor to donor. Published protocols using the promonocytic cell line THP-1 have tended to result in cells that closely resemble classically-activated macrophages, differentiated in IFNγ and LPS. However, no protocol, to date, has fully recapitulated polarization of THP-1 to the M(IL-4) or M(IL-10) macrophage phenotypes seen when human monocyte-derived macrophages are exposed to each cytokine. Here we present protocols that can be used to prepare M(IL-4) polarized THP-1 that transcribe CCL17, CCL26, CD200R and MRC1 and M(IL-10) cells which transcribe CD163, C1QA and SEPP1. We show that the inhibitory Fcγ Receptor IIb is preferentially expressed on the surface of M(IL-4) cells, altering the balance of activating to inhibitory Fcγ Receptors. Adoption of standardized experimental conditions for macrophage polarization will make it easier to compare downstream effector functions of different macrophage polarization states, where the impact of PMA exposure is minimized and rest periods and cytokine exposure have been optimized.
Insights
This study presents new protocols for polarizing THP-1 cells into M(IL-4) and M(IL-10) macrophage phenotypes, improving in vitro macrophage modeling for research. These standardized methods enhance the reliability of studying macrophage functions.
Area of Science:
- Immunology
- Cell Biology
Background:
- Human monocyte-derived macrophages are valuable for research but are short-lived and variable.
- Existing THP-1 cell differentiation protocols primarily yield classically-activated macrophages.
Purpose of the Study:
- To develop reliable protocols for polarizing THP-1 cells into M(IL-4) and M(IL-10) macrophage phenotypes.
- To establish standardized in vitro models for studying macrophage polarization and effector functions.
Main Methods:
- Utilized the promonocytic cell line THP-1.
- Optimized protocols involving rest periods and specific cytokine (IFNγ, LPS, IL-4, IL-10) exposure.
- Analyzed gene transcription (CCL17, CCL26, CD200R, MRC1, CD163, C1QA, SEPP1) and cell surface receptor expression (Fcγ Receptor IIb).
Main Results:
- Successfully generated M(IL-4) polarized THP-1 cells transcribing specific markers (CCL17, CCL26, CD200R, MRC1).
- Successfully generated M(IL-10) polarized THP-1 cells transcribing specific markers (CD163, C1QA, SEPP1).
- Demonstrated preferential expression of inhibitory Fcγ Receptor IIb on M(IL-4) cells, shifting the activating to inhibitory Fcγ Receptor balance.
Conclusions:
- Developed optimized protocols for M(IL-4) and M(IL-10) THP-1 cell polarization, overcoming limitations of previous methods.
- Standardized conditions minimize phorbol 12-myristate 13-acetate (PMA) impact and optimize cytokine exposure for reproducible macrophage research.
- These protocols facilitate comparative studies of downstream effector functions across different macrophage polarization states.
