Innate immunity
Innate immunity is the body's first line of defense against harmful invaders such as pathogens—viruses, bacteria, parasites, and fungi—as well as toxins. Also referred to as natural or genetic immunity, it is present at birth and does not require prior exposure or learning to be effective. The innate immune system responds quickly to threats through physical barriers like skin and mucous membranes, chemical defenses such as stomach acid and tears, and various cellular defenses provided by white blood cells. These components work together to neutralize and eliminate pathogens, often within the first week of exposure.
The innate immune response is generally non-specific, meaning it attacks all types of invaders in a similar manner, and it also helps activate the adaptive immune system, which develops targeted responses to specific pathogens. While innate immunity plays a crucial role in protecting overall health, it can sometimes lead to adverse reactions, such as allergies, when the system overreacts to harmless substances. Overall, innate immunity is essential for maintaining health and resilience against disease.
On this Page
Subject Terms
Innate immunity
Innate immunity is the first line of defense against harmful substances that enter the body. It is also known as natural immunity or genetic immunity. The innate immune system detects invaders known as pathogens and releases special cells that attack them. Innate immunity is present at birth, does not need to be learned, and can be very effective. The innate immunity system does not identify what type of attack is present and reacts in much the same way regardless of the substance present. It is still an important and valuable part of protecting against disease and illness caused by foreign substances.
Overview
The immune system is the body’s way of protecting against diseases caused by pathogens. Pathogens are organisms such as viruses, bacteria, parasites, and fungi. The immune system also protects against the effects of toxins such as poisons.
Immunity works in two ways: through innate immunity and through adaptive immunity. The innate immune system is present at birth and is the first line of defense. The adaptive immune system is activated by the innate immune system. Also known as acquired immunity, the adaptive immune system develops and remembers a response to specific pathogens. Both innate and adaptive immunity are important to protect a person’s overall health.
Innate immunity is coded into a person’s genes and provides protection from illness beginning at birth. The innate immune system begins to work almost immediately after exposure to a pathogen or toxin.
The innate immune response can come in the form of physical barriers, chemical barriers or cellular defenses against the invading pathogen or toxin.
- Physical barriers such as skin, eyelashes, and the hairs inside the nose interfere with the ability of a pathogen or toxin to enter the body. The coughing reflex creates a physical barrier by expelling potentially harmful substances.
- Chemical barriers include tears and nasal secretions. They help wash pathogens or toxins from the body. Stomach acid is another chemical barrier; it kills many types of pathogens that enter through the mouth into the digestive system.
- Cellular defenses in the white blood cells generate a variety of other cells that can attack pathogens. They include dendritic cells, mast cells, macrophages, neutrophils, basophils and eosinophils. These cells in turn produce other cells that weaken or kill invading pathogens.
The innate immune system works best in the first seven days after the introduction of a pathogen. It helps neutralize or kill pathogens, and helps attract cellular defenses to the part of the body where they are most needed. It also triggers the acquired immune system to develop specialized cells called antibodies to attack the pathogens, and helps the body eliminate dead cells as the immune system works.
The innate immune system is part of a healthy and efficient immune response to protect the body from illness. However, it can sometimes result in undesired responses. In some cases, the system will react to substances that are generally not harmful. When this unnecessary response is excessive, it results in allergies.
Bibliography
Cain, Phil. “How Does Your Immune System Work?” World Economic Forum, 7 Apr. 2020, www.weforum.org/agenda/2020/04/immune-system-fight-off-disease-coronavirus-covid19-pandemic/. Accessed 10 Feb. 2021.
Delves, Peter J. “Innate Immunity.” Merck Manual, April 2020,
www.merckmanuals.com/home/immune-disorders/biology-of-the-immune-system/innate-immunity. Accessed 10 Feb. 2021.
Gleichmann, Nicole. “Innate Vs. Adaptive Immunity.” Immunology and Microbiology, 20 May 2020, www.technologynetworks.com/immunology/articles/innate-vs-adaptive-immunity-335116. Accessed 10 Feb. 2021.
“Immune Response.” Medline Plus, 8 Feb. 2021, medlineplus.gov/ency/article/000821.htm. Accessed 10 Feb. 2021.
“Introduction to Immunology Tutorial. The Biology Project, University of Arizona, 24 May 2000, www.biology.arizona.edu/immunology/tutorials/immunology/page3.html. Accessed 10 Feb. 2021.
“Innate and Adaptive Immunity.” American Society for Radiation Oncology, 2021, www.astro.org/Patient-Care-and-Research/Research/Professional-Development/Research-Primers/Innate-and-Adaptive-Immunity. Accessed 10 Feb. 2021.
Shoman, Mary. “How the Immune System Works.” VeryWell Health, 4 July 2020, www.verywellhealth.com/how-does-the-immune-system-work-3232652. Accessed 10 Feb. 2021.
“What is Innate Immunity?” Center for Innate Immunity and Immune Diseases, ciiid.washington.edu/content/what-innate-immunity. Accessed 10 Feb. 2021.
Bekempis, Victoria. “‘Could You Buy A Little Less, Please?’: Panic-Buying Disrupts Food Distribution.” Guardian, 23 March 2020, www.theguardian.com/world/2020/mar/23/us-coronavirus-panic-buying-food. 2 June 2020.