The Immune System and Its Role in Hepatitis

The immune system is a collection of organs, cells, and tissues that work together to protect your body from disease caused mostly by pathogens (bacteria, viruses, parasites, and fungi). Some parts of the immune system include your tonsils, lymph nodes, appendix, spleen, and thymus. In addition, specialized cells, called white blood cells, are on patrol throughout your body looking for pathogens.

The immune system is a very complex defense system and plays a direct role in immunization, infectious diseases, allergies, and autoimmune diseases. The immune system is involved in one way or another in patients with all types of hepatitis, whether as a cause or treatment for the disease.

Autoimmune diseases are the result of a process in which the immune system mistakes an organ or body system for an invader, and attacks it as such. This results in inflammation and damage to the organ. Hepatitis describes an inflammation of the liver. For people with viral hepatitis, a virus causes the immune system to react by attacking the virus and causing damage to the liver in the process. However, another cause of hepatitis is an autoimmune process that damages the liver.

Autoimmune hepatitis, when the body's immune system mistakes normal liver tissue for an invader and attacks accordingly, is a chronic disease that causes inflammation and liver damage. If left untreated, autoimmune hepatitis can worsen over time and lead to cirrhosis and liver failure. The disease can cause symptoms that resemble those of viral or other types of hepatitis such as:

• Fatigue
• Joint pain
• Nausea
• Loss of appetite
• Pain or discomfort over the liver
• Skin rashes
• Dark yellow urine
• Light-colored stools
• Jaundice, or yellowing of the skin and whites of the eyes

There are currently two vaccines to prevent against two different types of viral hepatitis—hepatitis A and hepatitis B. Vaccines, or immunizations, use a trigger (such as inactivated or weakened viral material) to create an immune response against the invader. The immune system then essentially has a developed and effective response available when a true pathogen becomes a threat.

For patients with chronic viral hepatitis, the goal of treatment is to prevent liver damage that occurs as a result of the immune system's response to the virus. One way modern medicine is able to achieve this goal is by using treatments, such as interferon alpha, that essentially stimulate the immune system to do a more effective job of attacking—and hopefully—eliminating the virus.