Dandruff Is Associated With Perturbations of Hair Follicle Immune Privilege and the Infundibular and Epidermal Immune Microenvironment

The study provides the first evidence that dandruff is associated with a weakened hair follicle immune privilege (HF IP), a reduction in the number of MHC class II+ Langerhans cells in the infundibulum, and epidermal infiltration of CD4+ and CD8+ T cells. The researchers analyzed the expression of HF IP biomarkers and guardians, and quantified intra- and perifollicular immune cells in healthy versus dandruff scalp biopsies (n= 5-8). They found increased MHC Class I and β2M protein expression in dandruff hair follicles, while the expression of the immunoinhibitory IP guardian, MIF, was decreased. CD4+ and CD8+ T cells were significantly increased in lesional dandruff epidermis, but the number of intra- and perifollicular CD68+ Macrophages, CD4+ and CD8+ T cells remained unchanged in dandruff scalp hair follicles.