Researchers from the Icahn School of Medicine at Mount Sinai, Weill Cornell Medicine and other institutions say they have uncovered a key biological explanationwhy eczema so often starts in childhood. The study, conducted on young mice, found that some types of immune cells in early-life skin are more reactive than those in adults. This difference may help explain why children are more vulnerable to inflammation and allergic skin disease, according to the study authors.    The findings were p...