The Anagen Hair Cycle Induces Systemic Immunosuppression of Contact Hypersensitivity in Mice

The study found that the anagen phase of the hair cycle in mice induced systemic immunosuppression, specifically inhibiting TH1 immune responses such as contact hypersensitivity. This phase of hair growth was associated with a state of relative immunosuppression in the skin, which could have implications for wound healing and immune privilege. The research suggested that the molecular environment of the anagen hair bulb, which includes various cytokines and neuropeptides, might play a role in this immunosuppressive effect.