The key difference between phagocytosis and opsonization is that phagocytosis is a mechanism executed by certain cells or organisms to ingest or engulf foreign particles while opsonization is the process by which pathogens are removed from the system upon being marked by means of opsonins.
Immunologic responses can be innate or adaptive. Pathogens possess pathogen recognition receptors that make it easier to be identified by the host. Opsonization and phagocytosis are two immunological responses. In opsonization, the host identifies and marks invading particles for destruction by the production of opsonins. Phagocytosis is a mechanism by which certain immune cells engulf and destroy invading particles or foreign particles from the body.
CONTENTS
1. Overview and Key Difference
2. What is Phagocytosis
3. What is Opsonization
4. Similarities Between Phagocytosis and Opsonization
5. Side by Side Comparison – Phagocytosis vs Opsonization in Tabular Form
6. Summary
What is Phagocytosis?
Phagocytosis is a defence mechanism executed by certain cells or organisms to remove foreign particles from the body. They ingest or engulf foreign particles and destroy them. Phagocytes are the cells that carry out phagocytosis. Phagocytes are types of white blood cells, especially, neutrophils, monocytes and macrophages present in the blood. These cells protect the body by detecting foreign particles such as bacteria, toxins, dead and dying somatic cells. Phagocytes then engulf and destroy them. In fact, phagocytes are part of the body’s’ immune system. They are produced in the bone marrow by mitotic cell division.
Figure 01: Phagocytosis
Phagocytosis is a kind of endocytosis process. By phagocytosis, solid particles are internalized into a structure called phagosome. Once they are trapped inside the phagosome, they fuse with a lysosome and forms a phagolysosome. Then using the lysosome hydrolase enzymes, particles inside the phagosome are degraded and destroyed.
Phagocytosis is an extremely important process in disposing of the dead somatic cells that have undergone programmed cell death. These cells should be disposed from the body to provide space for new cells. Therefore, it is mainly done by phagocytes in the body. Dead or dying cells release certain chemicals that can be detected by the nonprofessional phagocytes and ingested by phagocytosis. Meanwhile, professional phagocytes detect bacteria and other microbes from the body by phagocytosis. Viruses cannot be destroyed by phagocytosis since they use the same mechanism of phagocytosis to invade white blood cells and infect the host cells.
What is Opsonization?
Opsonization is the process which removes pathogens from the system upon being marked by means of opsonins. Opsonins are molecules that can recognize pathogens. Pathogens possess pathogen recognition receptors. Opsonins are present in phagocytes and help in recognizing pathogen recognition receptors. Some examples of opsonins are receptors such as Fc receptor and complement receptor 1 (CR1). Opsonins also have the capability to induce the complement pathway and activate phagocytosis.
Figure 02: Opsonization
Opsonins bind to the epitope of a pathogen. When opsonins bind to the pathogen, phagocytes are attracted to the pathogen and facilitate phagocytosis. Opsonization can also activate adaptive immune responses. Here, the antibody IgG binds to the opsonized pathogen. Thus, this allows the antibody-dependent cell-mediated cytotoxicity in cells. In the absence of opsonins, inflammation can take place and damage healthy tissues during infection.
What are the Similarities Between Phagocytosis and Opsonization?
- Phagocytosis and opsonization are immune responses.
- Foreign particles or invading pathogens are identified and targeted by opsonization for destruction by phagocytosis.
- Both processes are extremely important to protect from us from infections and diseases.
What is the Difference Between Phagocytosis and Opsonization?
Phagocytosis is the mechanism by which certain cells remove foreign particles by engulfing them and destroying. On the other hand, opsonization is the process by which pathogens are removed from the system upon being marked by means of opsonins. So, this is the key difference between phagocytosis and opsonization. Further, the cells involved in phagocytosis are phagocytes while molecules involved in opsonization are opsonins.
Below infographic summarizes the difference between phagocytosis and opsonization.
Summary – Phagocytosis vs Opsonization
Phagocytosis is a mechanism used by immune cells and certain organisms to engulf infectious particles and destroy them. Phagocytes carry out phagocytosis. It is kind of endocytosis that internalizes solid particles into a structure called phagosome. Meanwhile, opsonization is the mechanism by which invading particles are targeted for destruction through phagocytosis. Opsonin molecules carry out opsonization. This summarizes the difference between phagocytosis and opsonization.
Reference:
1. “Phagocytosis.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., Available here.
2. Stoakes, Shelley Farrar. “Overview of Opsonization.” News, 23 Aug. 2018, Available here.
Image Courtesy:
1. “Neutrophil with anthrax copy” By Volker Brinkmann – (November 2005). “Neutrophil engulfing Bacillus anthracis”. PLoS Pathogens 1 (3): Cover page. DOI:10.1371. Retrieved on 2009-01-04 (CC BY 2.5) via Commons Wikimedia
2. “Antibody Opsonization” By Maher33 – Own work (CC BY-SA 4.0) via Commons Wikimedia