Comparative Analysis of Human Epidermal and Peripheral Blood γδ T Cell Cytokine Profiles

BACKGROUND: Human epidermal γδ T cells are known to play crucial roles in the defense and homeostasis of the skin. However, their precise mechanism of action in skin inflammation remains less clear. OBJECTIVE: In this study, we analyzed the cytokine expression profile of human epidermal γδ T cells and compared it to that of peripheral blood γδ T cells to investigate the specific activity of epidermal γδ T cells in modulating skin inflammation. METHODS: We isolated γδ T cells from epidermal tissue or peripheral blood obtained from healthy volunteers. Isolated γδ T cells were stimulated using immobilized anti-CD3 antibody and interleukin-2 plus phytohaemagglutinin, and were then analyzed using a cytokine array kit. RESULTS: Both epidermal and peripheral blood γδ T cells produced comparable levels of granulocyte-macrophage colony-stimulating factor, I-309, interferon-γ, macrophage migration inhibitory factor, macrophage inflammatory protein-1α, and chemokine (C-C) ligand 5. The epidermal γδ T cells produced significantly higher levels of interleukin-4, -8, -13, and macrophage inflammatory protein-1β than the peripheral blood γδ T cells did. Notably, the epidermal γδ T cells produced several hundred-fold higher levels of interleukin-13 than interleukin-4. CONCLUSION: These results suggest that the epidermal γδ T cells have a stronger potential to participate in the Th2-type response than the peripheral blood γδ T cells do. Furthermore, epidermal γδ T cells might play an important role in the pathogenesis of Th2-dominant skin diseases because of their active production of interleukin-13.