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Updated: Jul 19, 2026
Study of Phagolysosome Biogenesis in Live Macrophages
Published on: March 10, 2014
High-throughput assays of phagocytosis, phagosome maturation, and bacterial invasion
Benjamin E Steinberg1, Cameron C Scott, Sergio Grinstein
1Program in Cell Biology, The Hospital for Sick Children, 555 Univ. Ave., Toronto, ON, Canada.
Abstract:
Ingestion of foreign particles by macrophages and neutrophils and the fate of the vacuole that contains the ingested material are generally monitored by optical microscopy. Invasion of host cells by pathogenic bacteria and their intracellular proliferation are similarly studied by microscopy or by plating assays. These labor-intensive and time-consuming methods limit the number of assays that can be performed. The effort required to test multiple reagents or conditions can be prohibitive. We describe high-throughput assays of phagocytosis and of phagosomal maturation. An automated fluorescence microscope-based platform and associated analysis software were used to study Fcgamma receptor-mediated phagocytosis of IgG-opsonized particles by cultured murine macrophages. Phagosomal acidification was measured as an index of maturation. The same platform was similarly used to implement high-throughput assays of invasion of mammalian cells by pathogenic bacteria. The invasion of HeLa cells by Salmonella and the subsequent intracellular proliferation of the bacteria were measured rapidly and reliably in large populations of cells. These high-throughput methods are ideally suited for the efficient screening of chemical libraries to select potential drugs and of small interference RNA libraries to identify essential molecules involved in critical steps of the immune response.
Insights
This study introduces high-throughput assays for phagocytosis and bacterial invasion, enabling faster screening of potential drugs and immune response molecules. These automated methods overcome limitations of traditional, time-consuming techniques.
Area of Science:
- Immunology
- Cell Biology
- Microbiology
Background:
- Traditional methods for studying phagocytosis and bacterial invasion, such as microscopy and plating assays, are labor-intensive and time-consuming.
- These limitations hinder the efficient screening of large compound or genetic libraries for drug discovery and understanding immune responses.
Purpose of the Study:
- To develop and validate high-throughput assays for quantifying phagocytosis and intracellular bacterial proliferation.
- To enable rapid and reliable assessment of cellular processes involved in host-pathogen interactions and immune responses.
Main Methods:
- Utilized an automated fluorescence microscope-based platform with associated analysis software.
- Assessed Fcgamma receptor-mediated phagocytosis of IgG-opsonized particles by murine macrophages, measuring phagosomal acidification as an index of maturation.
- Implemented high-throughput assays for measuring the invasion and subsequent intracellular proliferation of pathogenic bacteria (e.g., Salmonella) in mammalian cells (e.g., HeLa cells).
Main Results:
- Demonstrated the capability of the platform to perform high-throughput assays for phagocytosis and phagosomal maturation.
- Successfully applied the platform to rapidly and reliably measure bacterial invasion and proliferation in large cell populations.
- Validated the efficiency of these high-throughput methods for screening chemical and small interference RNA libraries.
Conclusions:
- The developed high-throughput assays significantly improve the efficiency of studying phagocytosis, phagosomal maturation, and host cell invasion by pathogens.
- These automated methods are crucial for accelerating drug discovery and identifying key molecules in immune response pathways.
- The platform offers a robust solution for large-scale screening in immunology and infectious disease research.
