Spontaneous hair follicle cycling may influence the development of murine contact photosensitivity by modulating keratinocyte cytokine production

The development of murine contact hypersensitivity is influenced by hair follicle cycling. Here, we have examined hair cycle-associated fluctuations of murine contact photosensitivity (CPS) to tetrachlorosalicylanilide (TCSA) and its immunologic mechanism(s). When the CPS outcome was monitored in correlation with their spontaneous, synchronized hair cycling, mice aged 8 and 14 weeks, with most of their hair follicles in telogen, exhibited strong CPS responses, whereas 4-, 11-, and 16-week-old mice with a predominance of anagen follicles in a large area of their integument exhibited lower responses. This suggests that the development of CPS is inhibited in mice with anagen hair follicles. Antigen-specific, T-cell receptor Vβ7⁺ suppressor T cells, which are recognized to down-regulate the CPS response to TCSA, were not generated in sensitized anagen mice. Culture supernatants of epidermal cells derived from mice with anagen hair follicles contained factor(s) that suppress in vive the development of CPS. It was found that levels of mRNA for tumor necrosis factor α (TNFα) were markedly decreased in epidermal cells from early anagen to telogen mice, whereas message for IL- 1 receptor antagonist (IL-1ra) was transcribed increasingly during this hair cycling. These findings suggest that altered keratinocyte production of these cytokines is involved in mediating the anagen-associated depression of CPS.