Immune cells play dual role in protection

Cambridge, Mass. - Langerhans cells (LCs), immune cells found in the skin, can be both helpful and harmful, allowing beneficial microbes to live as well as attacking harmful foreign bodies, depending on the situation, a new study proposes.

Previous studies were unclear on the specific role of TCs, partially because much existing research has been done on mice, whose LCs appear to serve a very different role than those of humans.

The study, published online in Immunity, utilized technical advancements in extracting large numbers of specific immune cells from human skin. Researchers then examined the function of LCs both under normal circumstances and in the presence of a pathogen. The study reports that under normal conditions, LCs aided in proliferation of T cells that regulate the immune system and prevent it from attacking normal, healthy skin. When a pathogen was present, however, LCs triggered a different type of T cell that encourages protective responses.

“Essentially, this means that LCs can apply the brakes to the immune response and maintain tolerance under normal conditions, but also have the capacity to push the gas and activate protective skin-resident T cells to mount an immune response when confronted with potentially harmful invaders,” the study authors wrote. “This context-specific response is perfectly suited to a cell like the LC, which is at the interface of the body and the environment.”

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