AUTHOR=Wan Feng , Hu Chong-bin , Ma Jun-xia , Gao Ke , Xiang Li-xin , Shao Jian-zhong 

TITLE=Characterization of γδ T Cells from Zebrafish Provides Insights into Their Important Role in Adaptive Humoral Immunity

JOURNAL=Frontiers in Immunology

VOLUME=7

YEAR=2017

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2016.00675

DOI=10.3389/fimmu.2016.00675

ISSN=1664-3224

ABSTRACT=<p>γδ T cells represent an evolutionarily primitive T cell subset characterized by distinct T cell receptors (TCRs) and innate and adaptive immune functions. However, the presence of this T cell subset in ancient vertebrates remains unclear. In this study, γδ T cells from a zebrafish (<italic>Danio rerio</italic>) model were subjected to molecular and cellular characterizations. The constant regions of zebrafish TCR-γ (<italic>Dr</italic>TRGC) and δ (<italic>Dr</italic>TRDC) were initially identified. Zebrafish γδ T cells accounted for 7.7–20.5% of the total lymphocytes in spleen, head kidney, peripheral blood, skin, gill, and intestine tissues. They possess typical morphological features of lymphocytes with a surface phenotype of γ<sup>+</sup>δ<sup>+</sup>CD4<sup>−</sup>CD8<sup>+</sup>. Zebrafish γδ T cells functionally showed a potent phagocytic ability to both soluble and particulate antigens. They can also act as an antigen-presenting cell to initiate antigen (KLH)-specific CD4<sup>+</sup> T<sub>KLH</sub> cell activation and to induce B cell proliferation and IgM production. Particularly, zebrafish γδ T cells also play a critical role in antigen-specific IgZ production in intestinal mucus. These findings demonstrated that γδ T cells had been originated as early as teleost fish, which providing valuable insights into the evolutionary history of T cell subset. It is anticipated that this study would be used as a guide to develop a zebrafish model for the cross-species investigation of γδ T cell biology.</p>