Gamma-Delta T Cells Promote Wound Repair

Researchers have identified a wound repair function for gamma-delta T cells, the major T cell component of the skin, lung, and intestine. The findings, published in the April 26, 2002, issue of Science, may be pertinent to the treatment of diseases that arise from epithelial cell disorders, such as asthma, psoriasis, cancers, and inflammatory bowel disease
"Very little has been known about the function of these cells until now,” explained Dr. Wendy Havran, head of the research team from the Scripps Research Institute (La Jolla CA, USA).

Scientists knew that gamma-delta T cells arise early in fetal development in the thymus. From there, they migrate to the epithelial tissues that make up the outermost layers of the skin and line organs such as the intestines and lungs. Most gamma-delta T cells do not circulate through the bloodstream. While gamma-delta T cells are the first T cells the thymus produces, their production ceases later in development. The population of gamma-delta T cells is then maintained within the epithelial tissues. Unlike other T cells, which display many different types of receptors that recognize a wide diversity of antigens, the gamma-delta T cells in the skin seem to have little, if any, diversity and display a uniform receptor and recognize only a single antigen.

The new study showed that when skin is cut or damaged, epithelial cells called keratinocytes, common in the epidermis, release the antigen recognized by the gamma-delta cells. This activates the gamma-delta cells and they concentrate on producing growth factors that bind to keratinocytes and other epithelial cells, aiding their proliferation and leading to closure of the wound. The gamma-delta T cells also proliferate, multiplying to increase the response to the wound.

"When gamma-delta T cells are missing, you see a delay in wound repair,” said Dr. Havran, adding that the body still has other mechanisms to facilitate wound repair that eventually heal the wound.





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