Dermal V gamma T-+(4) cells enhance the IMQ-induced psoriasis-like skin inflammatidon in re-challenged mice

To investigate the role of dermal V gamma(+)(4)gamma delta 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 V gamma(-)(4) 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 V gamma(-)(4) depleted re-challenged group. In addition, the V gamma(+)(4)gamma delta T cells increased in number and secreted more IL-17A, gamma-IFN and IL-22 in the re-challenged control group compared with the primary challenged group. However, in the V gamma(-)(4) depleted re-challenged group, the V gamma(+)(4)gamma delta T cells increased in number and produced more IL-17A and IL-22 compared with re-challenged control mice. These findings suggest that dermal V gamma(+)(4)gamma delta T T cells enhance relapsing psoriasis-like skin inflammation induced by IMQ in C57BL/6 mice by secreting IL-17A and gamma-IFN.