What is a Macrophage?

Macrophages are important cells of the immune system that are formed in response to an infection or accumulating damaged or dead cells. Macrophages are large, specialized cells that recognize, engulf and destroy target cells. The term macrophage is formed by the combination of the Greek terms "makro" meaning big and "phagein" meaning eat.

Macrophage covering cancer cellImage Credit: Alpha Tauri 3D Graphics/Shutterstock.com

Formation of macrophages

Macrophages are formed through the differentiation of monocytes, one of the major groups of white blood cells of the immune system.

When there is tissue damage or infection, the monocytes leave the bloodstream and enter the affected tissue or organ and undergo a series of changes to become macrophages. These macrophages can modify themselves to form different structures in order to fight various different microbes and invaders. In this way, macrophages provide the first line of defense in protecting the host from infection.

The macrophages present in humans are around 21 micrometers in diameter. They can survive for months at a time. They are also involved in the development of non-specific or innate immunity.

This type of immunity is a long-term immunity which is acquired when a macrophage digests a microbe and presents the microbe's antigen on its surface to alert other white blood cells to the presence of the invading particle. Other white blood cells then multiply and amount an immune response against the pathogen.

In addition, the pathogen displaying the antigen can be recognized and targeted directly by antibodies should future reinfection occur, meaning that the pathogen is in a sense "remembered" by the immune system.

Each of the macrophages has specific protein markers on the cell surface. Some examples include CD14, CD11b, EMR1, MAC-1/MAC-3, Lysozyme M, and CD68. These markers can be identified using a technical process called flow-cytometry.

Function

Macrophages may have different names according to where they function in the body. For example, macrophages present in the brain are termed microglia and in the liver sinusoids, they are called Kupffer cells.

How do Immune Cells (Macrophages) Engulf Bacteria Phagocytosis Process

Further Reading

Last Updated: Nov 18, 2022

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.

Citations

Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Mandal, Ananya. (2022, November 18). What is a Macrophage?. News-Medical. Retrieved on June 01, 2023 from https://www.news-medical.net/life-sciences/What-is-a-Macrophage.aspx.

  • MLA

    Mandal, Ananya. "What is a Macrophage?". News-Medical. 01 June 2023. <https://www.news-medical.net/life-sciences/What-is-a-Macrophage.aspx>.

  • Chicago

    Mandal, Ananya. "What is a Macrophage?". News-Medical. https://www.news-medical.net/life-sciences/What-is-a-Macrophage.aspx. (accessed June 01, 2023).

  • Harvard

    Mandal, Ananya. 2022. What is a Macrophage?. News-Medical, viewed 01 June 2023, https://www.news-medical.net/life-sciences/What-is-a-Macrophage.aspx.

Comments

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
Post a new comment
Post
You might also like...
Small vesicles released by intestinal bacteria induce immune activation and progression of liver cirrhosis