Dendritic Cells Drive Early Eczema Development, Study

A team led by researchers from the Icahn School of Medicine at Mount Sinai has identified a biological reason eczema so often begins in early childhood. In experiments with young mice, scientists found that immune cells in developing skin—specifically dendritic cells—respond far more strongly to allergens than those in adults. This increased sensitivity may explain why children are more vulnerable to inflammation and allergic skin disease that can later progress into other allergic conditions.

Published in Nature, the findings suggest that early life represents a key window when the skin’s immune system is especially reactive. Eczema affects nearly one in four children and often appears before other allergies such as asthma or food sensitivities. The new study helps clarify why the disease is so closely linked to early development. 

“We found that allergy risk is shaped very early in life, when the skin’s immune system is biologically programmed to overreact to allergens, with important consequences for understanding how immune-mediated diseases emerge and should be treated,” said senior study author Shruti Naik. “By pinpointing the cells and hormonal signals that control this window of vulnerability, we open the door to strategies that could prevent allergic disease before it spreads from the skin to the lungs, gut, and beyond.”

To explore the mechanism, researchers exposed young mice to common allergens such as dust mites and mold. Unlike adult mice, the young mice developed strong skin inflammation. The team identified dendritic cells as the primary drivers of this response. These cells, unusually active early in life, triggered allergic inflammation unless their signaling pathway was blocked—an intervention that prevented skin allergies in the mice. 

The researchers also found that younger animals lacked typical levels of stress hormones that normally help restrain immune reactions. Similar immune activity was observed in skin samples from children with early-onset eczema but not in adults, pointing toward a similar process in humans. 

“Beyond eczema, this study reinforces a critical point for medicine,” says Dr. Naik. “Children are not simply small adults when it comes to immunity. Their immune system follows a unique set of rules, and recognizing that difference is essential for understanding—and ultimately preventing—allergic, immune-driven diseases that begin in childhood.”