AUTHOR=Wang Hong , Li Jing , Dong Xiaojing , Zhou Xaoqing , Zhao Lei , Wang Xiao , Rashu Rasheduzzaman , Zhao Weiming , Yang Xi 

TITLE=NK Cells Contribute to Protective Memory T Cell Mediated Immunity to Chlamydia muridarum Infection

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=10

YEAR=2020

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2020.00296

DOI=10.3389/fcimb.2020.00296

ISSN=2235-2988

ABSTRACT=<p>We previously reported that NK cells can promote type 1 T cell immune response that is essential for protection to a primary infection of <italic>Chlamydia muridarum</italic>. In this study, we have investigated the contribution of NK cells to memory T cells associated immunity during chlamydial infection. We have found that NK cell depletion led to impaired production of IFN-γ by memory T cells upon re-stimulation with chlamydial antigens <italic>in vitro</italic>. Mice with depleted NK cells also exhibited reduced type 1 T cell recall responses, with increased production of IL-4 from CD4<sup>+</sup> T cells and a lower level of <italic>Chlamydia</italic>-specific IgG2a titers compared to control mice. In addition, Tregs response was significantly increased in mice with NK cell depletion. Moreover, NK cell-depleted mice showed an increased bacterial loads and more severe inflammatory pathological changes than control mice. These findings indicate that NK cells contribute to protective memory T cell associated immunity to chlamydial re-infection through modulating the cytokine pattern of T cell and inhibition of Tregs response.</p>