FRIDAY, Aug. 11, 2006 (HealthDay News) -- Regulatory T cells, which "police" the immune system, are produced in the thymus and not from other circulating T cells, researchers report.
The study also provides new information about how mistakes made by regulatory T cells may contribute to autoimmune disease.
The findings suggest that it may one day be possible to control the early education of regulatory T cells in children in order to prevent autoimmune diseases, according to a team from the Medical College of Georgia.
It may also be possible to introduce new regulatory T cells into people with autoimmune disease, they said.
The thymus, a small organ located in the upper/front portion of the chest, is involved in the production and maturation of T cells during fetal development and childhood. Regulatory T cells direct the immune systems' roaming T cells.
Before regulatory T cells leave the thymus, they learn to distinguish between normal body tissue and invaders such as bacteria and viruses.
However, in some cases, regulatory T cells fail to learn how to recognize all the different kinds of normal body tissue, the Georgia group explained. This, along with environmental and other factors, can result in autoimmune diseases, where the body attacks its own tissues, the researchers said.
Lupus, arthritis, and type 1 diabetes are types of autoimmune diseases.
The MCG team found that, in mice, the regulatory T cell learning process in the thymus peaks in the first six weeks of life. That's about equivalent to the first 15 years of life in a human.
The early lessons, correct or not, learned by the regulatory T cells seem to last a lifetime. The few cells that develop later in life will likely behave like the earlier cell.
The study was published in the August issue of the journal Immunity.
The U.S. National Institute of Allergy and Infectious Diseases has more about the immune system.