AUTHOR=Pan Tingting , Tan Ruoming , Li Meiling , Liu Zhaojun , Wang Xiaoli , Tian Lijun , Liu Jialin , Qu Hongping TITLE=IL17-Producing γδ T Cells May Enhance Humoral Immunity during Pulmonary Pseudomonas aeruginosa Infection in Mice JOURNAL=Frontiers in Cellular and Infection Microbiology VOLUME=6 YEAR=2016 URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2016.00170 DOI=10.3389/fcimb.2016.00170 ISSN=2235-2988 ABSTRACT=

The host acquired immune response, especially the humoral immunity, plays key roles in preventing bacterial pneumonia in the lung. Our previous research demonstrated that interleukin 17-producing γδ T cells (IL17-γδ T cells) have a protective effect on the early innate immune response during acute pulmonary Pseudomonas aeruginosa infection. However, whether IL17-γδ T cells also play a role in humoral immunity is unknown. In this study, an acute pulmonary P. aeruginosa infection model was established in wild-type and γδ TCR−/− C57BL/6 mice. The expression of IL-17 on γδ T cells isolated from infected lung tissues increased rapidly and peaked at day 7 after acute infection with P. aeruginosa. Compared with wild-type infected mice, the levels of total immunoglobulins including IgA, IgG, and IgM in the serum and BALF were significantly decreased in γδ TCR−/− mice, with the exception of IgM in the BALF. Moreover, CD69 expression in B cells from the lungs and spleen and the level of BAFF in the plasma were also decreased in γδ TCR−/− mice. IL17-γδ T cell transfusion significantly improved the production of immunoglobulins, B cell activation and BAFF levels in γδ TCR−/− mice compared with γδ TCR−/− mice without transfusion; this effect was blocked when cells were pretreated with an IL-17 antibody. Together, these data demonstrate that IL17-γδ T cells are involved in CD19+ B cell activation and the production of immunoglobulins during acute pulmonary P. aeruginosa infection. Thus, we conclude that IL17-γδ T cells may facilitate the elimination of bacteria and improve survival through not only innate immunity but also humoral immunity.