Skin's Hidden Sentinels: Newly Identified Immune Cells Found in Hair Follicles
Key Findings
- Researchers at the University of California, Riverside School of Medicine discovered cells in mouse hair follicles that resemble M (microfold) cells—specialized epithelial cells previously known only in gut and airway tissues.
- The cells were identified within hair follicle epithelium and appear to participate in localized immune responses, particularly to Gram-positive bacteria.
- The findings were published in Frontiers in Cell and Developmental Biology.
A New Gateway for Immune Surveillance
The skin's stratified layers have long posed a question: how does effective immune surveillance occur through such a dense barrier? This new study proposes that hair follicles serve as localized "gateway" structures that concentrate environmental material and immune sensing activity.
"Hair follicles may represent a central hub for immune surveillance in the skin."
— David Lo, distinguished professor of biomedical sciences and senior author
The discovery of M-like cells within hair follicle epithelium suggests these structures are far more than anchors for hair—they may be active participants in the body's first line of defense.
Beyond the Gut and Airways
Until now, M cells were thought to be exclusive to the tissues lining the gut and airways. Their unexpected presence in the skin marks a significant expansion of our understanding. These cells appear to specialize in responding to Gram-positive bacteria, common microbes found on the skin's surface.
"Our study adds to growing evidence that epithelial barriers across tissues share more diverse and dynamic immune-related functions than previously recognized."
— Diana Del Castillo, graduate student and first author
What's Next
The research team plans to conduct detailed anatomical mapping of these cells, particularly in whisker follicles. Future investigations will focus on:
- Interactions with nerve and immune cells
- Whether similar systems exist in humans
If confirmed in human skin, this discovery could reshape our understanding of how the body monitors and responds to threats at its largest barrier—the skin itself.