Mast cells and γδ T cells are largely dispensable for adaptive immune responses after laser-mediated epicutaneous immunization

BackgroundThe skin resembles an attractive target for vaccination due to its accessibility and abundance of resident immune cells. Cells like {gamma}{delta} T cells and mast cells (MCs) are part of the first line of defence against exogenous threats. Despite being important mediators for eliciting TH2 immune responses after epithelial stress, {gamma}{delta} T cell and MC function still remains to be completely understood. Here, we aimed to characterize their roles in shaping adaptive immune responses after laser-mediated epicutaneous immunization (EPI).\n\nMethods{gamma}{delta} T cell knock out, MC depleted, and wildtype control mice were immunized with mannan-conjugated grass pollen allergen Phl p 5 (P5-MN) by laser-mediated EPI. After 2-3 immunizations, cytokine expression, T helper polarization, and antigen-specific IgG1/IgE levels were analysed. The local cytokine/chemokine milieu after laser microporation was determined.\n\nResultsWhile the majority of inflammatory chemokines and cytokines induced by laser treatment was not affected by the presence of {gamma}{delta} T cells or MCs, RANTES, was elevated in {gamma}{delta} T cell knock out mice, and GRO and TSLP, were significantly decreased after MC depletion. However, absence of {gamma}{delta} T cells or depletion of MC had no substantial effect on adaptive humoral or cellular immune responses after laser-mediated EPI, except for slightly reduced IgG1 and effector T cell levels in MC depleted mice.\n\nConclusions{gamma}{delta} T cells did not play a pivotal role in shaping the humoral and cellular adaptive immune response after laser-mediated EPI, whereas MC depletion decreased numbers of effector T cells, indicating a potential role of MCs in the activation and maturation of T cells after EPI.\n\nHighlightsO_LILaser microporation induces an inflammatory chemokine milieu at the site of immunization\nC_LIO_LI{gamma}{delta} T cells and mast cells contribute to the steady-state or damage-induced cytokine milieu in the skin\nC_LIO_LI{gamma}{delta} T cells and mast cells are dispensable for adaptive immunity after laser-mediated immunization\nC_LI