Faulty Immune-Boosting Cells Initiate Autoimmunity

The failure of programming that triggers the death of dendritic cells, those that activate the immune system, can initiate autoimmune disease, according to researchers in a recent report that appears in the February 24, 2006, issue of the journal Science.
The problem begins with a process called programmed cell death, or apoptosis, according to Dr. Jin Wang, assistant professor of immunology at Baylor College of Medicine (Houston, TX, USA). Mice engineered to have a defect in apoptosis of their dendritic cells went on to develop autoimmune disease, Dr. Wang said. "This suggests that defective apoptosis of dendritic cells can be a critical component of autoimmune diseases.”

Autoimmune diseases, such as lupus and juvenile diabetes, occur when the immune system begins attacking the body's own tissues instead of foreign organisms. "We knew that autoimmunity in general can be caused when dendritic cells are unchecked, either by programmed cell death or overactivation,” said Dr. Wang. "Dendritic cells are the initiators of immunity.” They do this by showing or presenting foreign antigens from invading bacteria or viruses to the immune system, which then triggers lymphocytes to attack.

Before this, many scientists believed autoimmunity occurred through apoptosis because of accumulating lymphocytes or white blood cells--major components of the immune system. "If they didn't die, we thought they would start to accumulate and do damage to the body's own tissues,” Dr. Wang stated. However, at least eight studies that suppressed programmed cell death in lymphocytes did not induce autoimmune disease in animals.

In the future, Dr. Wang and his colleagues plan to fill in the gaps between what occurs when apoptosis is hindered in the dendritic cells and the occurrence of autoimmune disease.



Related Links:
Baylor College of Medicine