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# 13.55: Autoimmune Diseases

Difficulty Level: At Grade Created by: CK-12
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Joint pain. Not an uncommon problem as you grow older. Is it due to normal wear and tear on the joints? Possibly. But rheumatoid arthritis is an autoimmune disease, which means the body's immune system mistakenly attacks healthy tissue.

### Autoimmune Diseases

Autoimmune diseases occur when the immune system fails to recognize the body’s own molecules as “self,” or belonging to the person. Instead, it attacks body cells as though they were dangerous pathogens. Some relatively common autoimmune diseases are listed in Table below . These diseases cannot be cured, although they can be treated to relieve symptoms and prevent some of the long-term damage they cause.

Name of Disease Tissues Attacked by Immune System Results of Immune System Attack
Rheumatoid arthritis tissues inside joints joint damage and pain
Type 1 diabetes insulin-producing cells of the pancreas inability to produce insulin, high blood sugar
Multiple sclerosis myelin sheaths of central nervous system neurons muscle weakness, pain, fatigue
Systemic lupus erythematosus joints, heart, other organs joint and organ damage and pain

Why does the immune system attack body cells? In some cases, it’s because of exposure to pathogens that have antigens similar to the body’s own molecules. When this happens, the immune system not only attacks the pathogens. It also attacks body cells with the similar molecules.

### Summary

• Autoimmune diseases occur when the immune system fails to distinguish self from non-self. As a result, the immune system attacks the body’s own cells.

### Practice

Use this resource to answer the questions that follow.

• http://www.hippocampus.org/Biology $\rightarrow$ Biology for AP* $\rightarrow$ Search: Disorders of the Immune System
1. What is an autoimmune disease?
2. What is meant by antibody mediated autoimmune disease ?
3. What are cell mediated autoimmune diseases?

### Review

1. What is an autoimmune disease? Name an example.

2. Rheumatic fever is caused by a virus that has antigens similar to molecules in human heart tissues. When the immune system attacks the virus, it may also attack the heart. What type of immune system disease is rheumatic fever? Explain your answer.

### Vocabulary Language: English Spanish

antigen

antigen

Molecule that the immune system identifies as foreign and responds to by forming antibodies.
autoimmune disease

autoimmune disease

Type of disease, such as type 1 diabetes, in which the immune system attacks the body’s cells as though they were pathogens.
pathogen

pathogen

Disease-causing agent such as a bacterium, virus, fungus, or protozoan.

Feb 24, 2012

Nov 02, 2015