T cells regrow hair in alopecia areata

Researchers have discovered that regulatory T lymphocytes can trigger a hair regrowth mechanism in cases of alopecia areata.

Scientists at the Salk Institute in California discovered by chance that regulatory T cells had the ability to re-grow hair in cases of hair loss induced by alopecia areata (alopecia areata). This specific type of alopecia is triggered by an anomaly of the immune system and is characterized by hair loss in patches, of varying sizes, in several places on the scalp (when alopecia areata affects the whole head, we speak of alopecia totalis). According to a 2004 publication, there are approximately 78,000 cases of alopecia areata in France, affecting patients aged 2 to 94. The publication shows how regulatory T lymphocytes, best known for their role in the immune system, are also capable of orchestrate hair growth by using a hormone as a messenger to the hair follicles.

For a long time, regulatory T cells have been studied in the context of excessive immune reactions. They are indeed a little special: while immune cells generally fight external attacks, regulatory T lymphocytes are responsible for inhibiting an immune reaction that would be too strong. A way to limit inflammation. When this function is disturbed, a pathology can occur: allergies, for example, are reactions of the immune system to a substance, which are totally disproportionate. Inflammation is also involved in alopecia areata. In cases of acute alopecia, immune cells attack the skin tissue. Existing treatments, based on glucocorticoids, consist in inhibiting the immune reaction of the skin so as not to continue attacking the hair follicles.