V Gamma 4+T Cells: A Novel Il-17-Producing Gamma Delta T Subsets During The Early Phase Of Chlamydial Airway Infection In Mice

Our previous studies showed that gamma delta T cells provided immune protection against Chlamydial muridarum (Cm), an obligate intracellular strain of chlamydia trachomatis, lung infection by producing abundant IL-17. In this study, we investigated the proliferation and activation of lung gamma delta T cell subsets, specifically the IL-17 and IFN gamma production by them following Cm lung infection. Our results found that five gamma delta T cell subsets, V gamma 1+ T, V gamma 2+ T, V gamma 4+ T, V gamma 5+ T, and V gamma 6+ T, expressed in lungs of naive mice, while Cm lung infection mainly induced the proliferation and activation of V gamma 4+ T cells at day 3 p. i., following V gamma 1+ T cells at day 7 p. i. Cytokine detection showed that Cm lung infection induced IFN gamma secretion firstly by V gamma 4+ T cells at very early stage (day 3) and changed to V gamma 1+ T cells at midstage (day 7). Furthermore, V gamma 4+ T cell is the main gamma delta T cell subset that secretes IL-17 at the very early stage of Cm lung infection and V gamma 1+ T cell did not secrete IL-17 during the infection. These findings provide in vivo evidence that V gamma 4+ T cells are the major IL-17 and IFN gamma-producing gamma delta T cell subsets at the early period of Cm lung infection.