Hair loss is a problem experienced by countless men and women, and as with any dilemma, figuring out the root cause is key to solving it. Recently, researchers from the University of California, San Francisco accidentally did just that when a standard investigation into immune cells revealed a previously unknown cause of baldness.

In the study, now published online in Cell, the UCSF team discovered that regulatory Treg T cells, a type of immune cell, are also directly involved with stimulating skin to grow healthy hair. In their study, the team found that when these cells were removed, stem cells were no longer able to regenerate hair follicles, which led to baldness. Previously, it was thought that stem cells cause hairs to regrow after they fall out, but the new research shows this is only the case when Tregs are present, The Independent reported.

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Based on these results, the team now believe that certain Tregs could be responsible for several types of hair loss, such as alopecia areata, and even common male pattern baldness. The team wants to further explore if these Tregs could also hold the key to repairing hair loss.

“Our hair follicles are constantly recycling: when a hair falls out, the whole hair follicle has to grow back,” said senior author Michael Rosenblum, in a new statement. “This has been thought to be an entirely stem cell-dependent process, but it turns out Tregs are essential. If you knock out this one immune cell type, hair just doesn’t grow.”

The study was originally meant to investigate the role of Tregs in protecting skin health. The team removed Tregs from skin to examine the effect it had on immune health, but they didn't expect to see the effect Tregs had on hair growth. 

We quickly noticed that the shaved patches of hair never grew back, and we thought, ‘Hmm, now that’s interesting,’” Rosenblum said. “We realized we had to delve into this further.”

Their investigation revealed that the genes associated with alopecia were almost all related to Tregs. What’s more, past research also revealed that treatments that boost Treg function also were effective in treating alopecia. Though the research is still new, the team believe that further studying the role of Tregs and their relationship to hair growth could soon lead to more effective hair loss treatments.

Alopecia areata is a type of hair loss that occurs when the immune system accidentally attacks hair follicles, WebMD reported. The condition is usually characterized by hair falling out in clumps to reveal totally smooth, hairless patches on the head and body. In some forms of the condition, hair does not fall out completely but rather becomes very thin, or breaks off leaving short stubs. The hair loss is not usually permanent, but for about 10 percent of people with the condition, the hair may never regrow.

Source: Ali N, Zirak B, Sanchez R, et al. Regulatory T Cells in Skin Facilitate Epithelial Stem Cell Differentiation. Cell . 2017

See Also:

Why Hair Loss Is More Common In Men, And What You Can Do About It

A Cure for Male Pattern Baldness? Not Yet, but Trigger for Hair Growth Found