IL-1 alpha inhibits human hair follicle growth and hair fiber production in whole-organ cultures.

The study demonstrated that IL-1 alpha significantly inhibited human hair follicle growth and hair fiber production in a whole-organ culture system. When exposed to 10 ng/ml IL-1 alpha, hair follicle growth stopped within 2-4 days, compared to 7-10 days in controls. Hair fiber growth inhibition occurred 3 days after follicle growth inhibition. The IC50 value for IL-1 alpha was approximately 30 pg/ml. IL-1 alpha also caused a rapid, temporary decrease in DNA synthesis in hair follicles. The inhibition was prevented by a 1000-fold molar excess of IL-1 receptor antagonist. The findings suggested that IL-1 alpha has a direct antiproliferative effect on hair follicles, potentially contributing to inflammatory hair loss conditions like alopecia areata.