LSC Abstract – CD3brightγδ T cells are early IL-17A-producers during acute pneumococcal infection

Interleukin-17A is a pro-inflammatory cytokine that plays an important role at mucosal sites in a wide range of immune responses including infection, allergy and auto-immunity. γΔ T cells are recognized as IL-17 producers, but based on the level of CD3 expression we have recently defined the remarkable ability of a pulmonary CD3 bright Vγ6/VΔ1 + T cell subset with an effector memory phenotype to rapidly produce IL-17A. During pulmonary pneumococcal infection, we show that CD3 bright Vγ6/VΔ1 + γΔ T cells are the major source of IL-17A during the early course of infection in a mechanism involving IL-23 and IL-1β. These two cytokines are preferentially produced by conventional dendritic cells and neutrophils. Moreover their rapid response to infection might be explained by their particular localization in the lung tissue. Unlike, other innate-like T cells that preferentially reside in the lung tissue as marginated cells, CD3 bright γΔ T cells are almost exclusively represented in the interstitial compartment. Finally, we are currently investigating the role of IL-17-producing CD3 bright γΔ T cells during acute pneumococcal infection. In the future, this might lead to the design of new prophylactic/therapeutic strategies employing tailored γΔ T cell-based immunotherapy.