Related Experiment Video
Updated: Aug 6, 2026
Polarization of M1 and M2 Human Monocyte-Derived Cells and Analysis with Flow Cytometry upon Mycobacterium tuberculosis Infection
Published on: September 18, 2020
Dynamics of macrophage cell populations during murine pulmonary tuberculosis
Mercedes Gonzalez-Juarrero1, Tae Sun Shim, Andre Kipnis
1Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA. malba@lamar.colostate.edu
Insights
Macrophages in the lungs are key to tuberculosis (TB) infection. This study identifies distinct macrophage populations in mice, revealing poor activation markers during chronic TB, impacting lesion breakdown and reactivation disease.
Area of Science:
- Immunology
- Cell Biology
- Infectious Diseases
Background:
- Macrophage influx is central to the granulomatous response in Mycobacterium tuberculosis infection.
- Understanding macrophage heterogeneity is crucial for dissecting host-pathogen interactions in TB.
Purpose of the Study:
- To define and characterize distinct macrophage populations in the lungs during Mycobacterium tuberculosis infection using flow cytometry.
- To investigate the activation phenotypes of these macrophage populations during early and chronic stages of infection.
Main Methods:
- Flow cytometric analysis of lung cells from infected mice using cell surface markers (CD11b, CD11c).
- Cell sorting for morphological definition of identified macrophage populations.
- Comparison of macrophage phenotypes during early and chronic infection stages.
Main Results:
- Distinguished alveolar macrophages (CD11b-/CD11c+/high), dendritic cells (CD11bhigh/CD11c+/high), and small macrophages/monocytes (CD11b+/mid/CD11c+/mid).
- Observed poor expression of Ag-presenting class II and activation markers on these populations during chronic TB.
- Identified changes in macrophage activation phenotypes over the course of infection.
Conclusions:
- The analytical approach allows for detailed characterization of lung macrophage populations in TB.
- Poorly expressed activation markers on macrophages during chronic infection may contribute to lesion breakdown and reactivation.
- Further characterization of these populations can elucidate their role in host resistance to tuberculosis.
Abstract:
The influx of macrophages into the lungs is the major component of the granulomatous response to infection with Mycobacterium tuberculosis. In this investigation we used flow cytometric analysis to define macrophage populations entering the airways and lung tissues of infected mice. We demonstrate that by the judicious use of cell surface markers, especially CD11b and CD11c, several cell populations can be distinguished, allowing cell sorting and morphological definition. Primary populations of CD11b(-)/CD11c(+/high) were defined as alveolar macrophages, CD11b(high)/CD11c(+/high) as dendritic cells, and CD11b(+/mid)/CD11c(+/mid) as small macrophages or monocytes, and changes in the activation phenotype of these populations were followed over the early course of the infection. In further studies, these cell populations were compared with cells harvested during the chronic stage of the disease. During the chronic stage of infection, Ag-presenting class II molecules and activation markers were poorly expressed on dendritic, small macrophage, and monocyte cell populations, which may have important implications for the breakdown of the lesions during reactivation disease. This analytical approach may facilitate the further characterization of macrophage populations entering into the lung tissues and their relative contributions to host resistance to tuberculosis infection.
Related Concept Videos
01:28Pulmonary Tuberculosis II
Here is a detailed explanation of its pathophysiology:
Transmission: The process begins when a person inhales droplet nuclei containing M. tuberculosis. These are typically released into the air when an individual with pulmonary or...
01:23Tuberculosis