B Cells and Autoimmune Diseases

Nearly 24 million people throughout the United Statessuffer from an autoimmune disease, and most of these people are women. A recent study suggests that B cells in the immune system may explain why women are so much more likely to suffer from autoimmune diseases than men are.

There are more than 80 various types of autoimmune diseases that exist today. They are described as conditions which cause the immune system to fail in a way which prevents the immune system from properly distinguishing between what is self and what is foreign. When this happens, the body begins creating autoantibodies which then attack healthy cells on accident. Basically autoimmune diseases are diseases in which the immune system attacks itself.

While the immune system is attacking itself, T cells which help to regulate the immune system and help it to run properly fail to work. The damage that this causes to the body shows itself through one of many autoimmune diseases. Some conditions that are autoimmune diseases include rheumatoid arthritis, multiple sclerosis, celiac disease, lupus, and type 1 diabetes.

Researchers at National Jewish Health found a specific type of B cell while they were researching X-chromosome genes in healthy mice. Researchers found that this type of B cell produces autoantibodies which attach themselves to and then attack the tissue within the body.

Among further research, they found that this type of B cell is found in much higher levels in the female mice and that those mice were then more likely to suffer from an autoimmune disease. Humans with autoimmune disease were also found to have more of these B cells. In male mice that were considered healthy, these B cells were found at steady low levels.

As female mice get older, the B cells were shown to increase. Because of this, the researchers named this cell Age-Associated B Cells (ABC’s). Philippa Marrack, lead author and professor of immunology at National Jewish Health stated that these cells could prove to be extremely useful in helping to diagnose as well as treat autoimmune diseases. It also may help researchers gain a better understanding of the basic mechanisms which underlie autoimmunity.

Researchers also discovered that they could detect higher levels of these ABC cells before a disease even began to develop which suggests that these cells could be used to detect autoimmune diseases in the earliest stages possible. In their research with the mice, they found that if they directly decreased the ABC’s in the mice, then their levels of autoantibodies also decreased, indicating a possible and promising way to treat autoimmune diseases. Because of all of their wonderful discoveries, National Jewish Health has already applied for a patent for the method used for B cell depletion as a treatment for autoimmune diseases.

The association between these cells and autoimmune diseases in women can be seen in the activation process of the B cells which requires stimulation of a cell surface receptor known as TLR7. TLR7 is found on the X chromosome which women have two of, while men only have one.

The fact that B cells are more prevalent in women and have to be activated by a gene that women generally have more of is extremely important and can perhaps explain why so many more women suffer from autoimmune diseases than men.

Reference:

Mitchell, D. 2011. Women get autoimmune disease more, b cells may be why.