immune system

American  

noun

Anatomy.

• immune systems
  plural

1. a diffuse, complex network of interacting cells, cell products, and cell-forming tissues that protects the body from pathogens and other foreign substances, destroys infected and malignant cells, and removes cellular debris: the system includes the thymus, spleen, lymph nodes and lymph tissue, stem cells, white blood cells, antibodies, and lymphokines.

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immune system Scientific  

1. The body system in humans and other animals that protects the organism by distinguishing foreign tissue and neutralizing potentially pathogenic organisms or substances. The immune system includes organs such as the skin and mucous membranes, which provide an external barrier to infection, cells involved in the immune response, such as lymphocytes, and cell products such as lymphokines.

2. See also autoimmune disease immune response

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immune system Cultural  

1. The system in the body that works to ward off infection and disease. Central to this system are the white blood cells. Some white blood cells produce antibodies in response to specific antigens that may invade the body; others function as scavengers to fight infection by destroying bacteria and removing dead cells.

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Other Word Forms

Noun Inflected Forms

• immune systems
  plural

Etymology

Origin of immune system

First recorded in 1960–65

Example Sentences

See Examples For:

immune system

When arginine is scarce, cells struggle to produce MHC-1, a protein that helps alert the immune system to threats such as mutated cells and invading viruses.

From Science Daily ● Aug. 3, 2026

This releases flares that train the immune system to track down and kill cancer cells hiding around the body.

From The Wall Street Journal ● Jul. 31, 2026

He also said regulators, including the state, have “been inadequate with respect to evaluating immune system harm or the cumulative impacts of these very small PFAS.”

From Los Angeles Times ● Jul. 30, 2026

KPV is also touted as being good for gut health, tissue repair - including skin damage, like acne, and for regulating the immune system.

From BBC ● Jul. 24, 2026

Every individual person's immune system responded robustly to the vaccine.

From "1491" by Charles C. Mann