Why Does the Body Attack Itself?

Contributor: Hannah Brooks. Lesson ID: 12698

Armies are trained to attack the enemy. Sometimes, they mistakenly attack innocent civilians. The same can happen in your body, when the immune system turns on the innocent healthy cells in your body!


Life Science

learning style
personality style
Grade Level
Middle School (6-8), High School (9-12)
Lesson Type
Dig Deeper

Lesson Plan - Get It!


How does the body identify invaders? What happens in the case of mistaken identity or friendly fire?

The immune system works to keep you healthy by identifying and destroying pathogen invaders.

You learned how the body responds through three lines of defense and how we helped the body avoid disease in the first Related Lessons of our Immune System series, found in the right-hand sidebar. Remember that the immune response begins with the physical barriers like skin, chemical compounds, and hair. If invaders move past this barrier, they meet the inflammatory response, where tissues move resources like fluid and white blood cells to remove invaders. Finally, the immune response uses specific cells to attack and destroy invading pathogens.

The immune response works to protect our bodies, but what happens when the body is unable to recognize an invader from a body cell? A critical component of a healthy immune system is the ability to identify foreign cells and particles. When the body cannot differentiate between foreign and body cells, an individual can develop an autoimmune disease.

There are several autoimmune diseases, many of which have similar symptoms. They are all characterized by the use of immune cells to attack body tissues as foreign invaders.

Have you noticed the phrase, "Gluten free," on foods at the grocery store? Celiac's disease is an autoimmune disease where the body attacks the digestive tract in the presence of gluten. Gluten is a protein found in a lot of foods: breads, tortillas, flavorings, soups, soy sauce, and many others.

gluten chart

When an individual with Celiac's eats gluten, the body starts to attack the small intestine, where nutrients are absorbed into the body. The immune response destroys the special cells responsible for removing nutrients from food. These cells extend into the cavity of the digestive system and look like small hairs working to collect nutrients from the food materials passing through. When these cells are damaged, it causes extreme weight loss, hair loss, fatigue, and digestive issues.

gluten effects

Autoimmune diseases cause daily irritation and long-term complications. The immune system works to keep you healthy and functioning, but can also use your cells against you in autoimmune diseases. Patients with an autoimmune disease are unable to distinguish foreign invaders from body cells, which leads to symptoms and the need for treatment.

  • How does the immune system respond to a pathogen in a normal immune response?
  • How might this response damage tissues in an autoimmune disease?

In the Got It? section, you will watch a video and learn more about specific autoimmune responses.

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