Monday, May 12, 2008

Autoimmunity discussion

I have been doing nothing but goofing off for the last several posts. Time to get back to some serious content. 

When I first was diagnosed with Sjogren's Syndrome, I was hit by a flood of information regarding my health. I realized that once I understood a bit about immunity and autoimmunity, then it was easier for me to see the larger picture of the problems of autoimmune disease.  

The concept of autoimmunity and the diseases that it causes is complex.
To start this discussion it's most basic concepts, we first have to know more about a normal immune system. 

Our immune system protects us against germs and microorganisms. It is made up of a system of cells, organs, and tissues that work together to protect the body. An important part of this system includes special white blood cells, called lymphocytes.

The following excellent information was taken from The Body Basics: The Immune System

"There are two kinds of lymphocytes: the B lymphocytes and the T lymphocytes. Lymphocytes start out in the bone marrow and either stay there and mature into B cells, or they leave for the thymus gland, where they mature into T cells. B lymphocytes and T lymphocytes have separate jobs to do: B lymphocytes are like the body's military intelligence system, seeking out their targets and sending defenses to lock onto them. T cells are like the soldiers, destroying the invaders that the intelligence system has identified. Here's how it works.

Antigens are foreign substances that invade the body. When an antigen is detected, several types of cells work together to recognize and respond to it. These cells trigger the B lymphocytes to produce antibodies, specialized proteins that lock onto specific antigens. Antibodies and antigens fit together like a key and a lock.

Once the B lymphocytes have produced antibodies, these antibodies continue to exist in a person's body, so that if the same antigen is presented to the immune system again, the antibodies are already there to do their job. That's why if someone gets sick with a certain disease, like chickenpox, that person typically doesn't get sick from it again. This is also why we use immunizations to prevent getting certain diseases. The immunization introduces the body to the antigen in a way that doesn't make a person sick, but it does allow the body to produce antibodies that will then protect that person from future attack by the germ or substance that produces that particular disease.

Although antibodies can recognize an antigen and lock onto it, they are not capable of destroying it without help. That is the job of the T cells. The T cells are part of the system that destroys antigens that have been tagged by antibodies or cells that have been infected or somehow changed. (There are actually T cells that are called "killer cells.") T cells are also involved in helping signal other cells (like phagocytes) to do their jobs."

A normal, healthy immune system has the capability to recognize an antigen - or a substance foreign to the body - and kill or remove it. 

In autoimmune disease, the body identifies part of it's own tissues as being antigens, and the B and T cells attack those tissues.

There are several disease which are caused by autoimmunity. Lupus Erythematosus, Juvenile Diabetes, Multiple Sclerosis, Rheumatoid Arthritis, Celiac Disease, Crohn's Disease, and Sjogren's Syndrome are some of the most well known. There are many others. 

We now know that the B and T lymphocytes in people with Sjogren's Syndrome attack those cells which secrete substances in our body, such as tears, saliva, and mucous. It is not fully understood why more generalized body symptoms such as fatigue, thyroid, lung, liver, intestinal and joint problems also occur, although the answer most certainly lies somewhere in the immune system.

For more information about immunity and autoimmunity, read this interesting article by the Autoimmune Research Center at  Johns Hopkins.

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