Accumulation and activation of epidermal γδ T cells in a mouse model of chronic dermatitis is not required for the inflammatory phenotype

Chronic skin inflammation resulting from a defective epidermal barrier is a hallmark of atopic dermatitis (AD). We previously demonstrated that mice lacking FGF receptors 1 and 2 in keratinocytes (K5‐R1/R2 mice) develop an AD‐like chronic dermatitis as a result of an impaired epidermal barrier. Here, we show that γδ T cells, which rapidly respond to various insults, accumulate in the epidermis of K5‐R1/R2 mice before the development of histological abnormalities. Their number and activation further increase as the phenotype progresses, most likely as a consequence of increased expression of Il‐2 and Il‐7 and the stress‐induced proteins Rae‐1, H60c, Mult1, PlexinB2, and Skint1. To determine the role of γδ T cells in the skin phenotype, we generated quadruple mutant K5‐R1/‐R2 mice lacking γδ T cells. Surprisingly, loss of γδ T cells did not or only marginally affect keratinocyte proliferation, epidermal thickness, epidermal barrier function, and accumulation and activation of different immune cells in the skin of K5‐R1/R2 mice, possibly due to partial compensation by αβ T cells. These results demonstrate that γδ T cells do not contribute to the development or maintenance of chronic inflammation in response to a defect in the epidermal barrier.