Dermal Vγ4+T Cells Enhance the IMQ-induced Psoriasis-Like Skin Inflammatidon in Re-Challenged Mice.

To investigate the role of dermal Vγ4+γδ T cells in psoriasis-like skin inflammation induced by a re-challenge with imiquimod (IMQ), we compared the development of dermatitis induced by topical application of IMQ in primary challenged mice and re-challenged mice. We also compared the development of dermatitis induced by IMQ between re-challenged control mice and Vγ4- depleted re-challenged mice that had been initially subjected to IMQ-induced dermatitis 30 prior. We found that the IMQ-induced dermatitis was exacerbated in the re-challenged group compared with the primary challenged group and the Vγ4- depleted re-challenged group. In addition, the Vγ4+γδ T cells increased in number and secreted more IL-17A, γ-IFN and IL-22 in the re-challenged control group compared with the primary challenged group. However, in the Vγ4- depleted re-challenged group, the Vγ4-γδ T cells increased in number and produced more IL-17A and IL-22 compared with re-challenged control mice. These findings suggest that dermal Vγ4+γδ T cells enhance relapsing psoriasis-like skin inflammation induced by IMQ in C57BL/6 mice by secreting IL-17A and γ-IFN.