IL-17⁺ γδ T cells as kick-starters of inflammation

Shortly after the discovery of interleukin 17 (IL-17)-producing CD4⁺ helper T cells (T_H17 cells), it was found that γδ T cells can also secrete large amounts of this pro-inflammatory cytokine. A decade later, it is now known that IL-17⁺ γδ T cells (γδ17 T cells) are often the main providers of IL-17A in various models of inflammatory diseases, while they also contribute to protective immune responses to infectious organisms. Due to an intricate thymic program of differentiation, γδ17 T cells are able to respond faster than T_H17 cells do and thus predominate in the early stages of inflammatory responses. Here we review the current knowledge of the development, activation and pathophysiological functions of γδ17 T cells, aiming to increase the awareness in the community of the therapeutic potential of this 'other side' of IL-17-mediated immune responses.