What are macrophages?

Toppage
Macrophages

What are macrophages?

In recent years, attention has been focused on "immunity," particularly since the onset of the novel coronavirus pandemic. Among immune cells, the term "macrophage" has also become recognized as referring to cells that fight against foreign substances invading the body. However, most know little about how immunity actually works and what roles macrophages play. This page includes simple explanations of macrophages, using illustrations to help even the general public with no medical knowledge easily understand.

01How "immunity" works

"Immunity" is a system that attacks and eliminates foreign substances, such as bacteria and viruses, that have entered the body from the outside, as well as abnormal cells, like cancer cells, that have developed within the body, thereby protecting the body from disease. Different types of cells are involved in immunity, which can be roughly divided into "innate immunity" and "acquired immunity." Innate immunity is responsible for monitoring the body for foreign substances and for initiating early responses. Acquired immunity involves recognizing the characteristics of foreign substances and producing antibodies to tailor the immune response to the specific characteristics of the foreign substance.

02Macrophages are the "body's cleaners"

Macrophages play a central role in "innate immunity." These are a type of white blood cell that exists throughout the body and eliminate pathogens such as bacteria and viruses that have entered the body, as well as abnormal cells such as tumors.

1. Patrol

Macrophages are distributed throughout the body and are constantly watching for foreign substances entering the body.

2. Eat invading foreign substances

Macrophages are called the "body's cleaners" because they eat and process "disease-causing substances."
"Disease-causing substances" include, for example:

・Bacteria or viruses that enter the body
・Cells infected with pathogens or viruses
・Foreign substances generated within the body, including tumor cells such as cancer
・Dead cells (apoptotic cells)

and the like

3. Communicate information about foreign substances found to other immune cells

When they find foreign substances, they do not just eat and process them, they also attach fragments of the foreign substance to their surface (this is called presentation) to inform other cells of the invading foreign substance. When fragments of the foreign substance presented are found, acquired immunity, such as T cells, begins to prepare for an attack.

What are macrophages?