Distinct Features of Canine Non-conventional CD4-CD8?- Double-Negative TCR??+ vs. TCR??+ T Cells.
Ontology highlight
ABSTRACT: The role of conventional TCR??+CD4+ or TCR??+CD8?+ single-positive (sp) T lymphocytes in adaptive immunity is well-recognized. However, non-conventional T cells expressing TCR?? or TCR?? but lacking CD4 and CD8? expression [i.e., CD4-CD8?- double-negative (dn) T cells] are thought to play a role at the interface between the innate and adaptive immune system. Dn T cells are frequent in swine, cattle or sheep and predominantly express TCR??. In contrast, TCR??+ T cells are rare in dogs. In this study, we identified a high proportion of canine dn T cells in the TCR??+ T cell population of PBMC, lymphatic and non-lymphatic organs. In PBMC, the frequency of this T cell subpopulation made up one third of the frequency of TCR??+CD4+ sp, and almost half of the frequency of TCR??+CD8?+ sp T cells (i.e., ~15% of all TCR??+ T cells). Among TCR??+CD4-CD8?- dn T cells of PBMC and tissues, FoxP3+ cells were identified indicating regulatory potential of this T cell subset. 80% of peripheral blood FoxP3+TCR??+CD4-CD8?- dn T cells co-expressed CD25, and, interestingly, also the FoxP3-negative TCR??+CD4-CD8?- dn T cells comprised ~34% CD25+ cells. Some of the FoxP3-positive TCR??+CD4-CD8?- dn T cells co-expressed GATA-3 suggesting stable function of regulatory T cells. The frequency of GATA-3 expression by FoxP3-TCR??+CD4-CD8?- dn T cells was even higher as compared with TCR??+CD4+ sp T cells (20.6% vs. 11.9%). Albeit lacking FoxP3 and CD25 expression, TCR??+CD4-CD8?- dn T cells also expressed substantial proportions of GATA-3. In addition, TCR??+CD4-CD8?- dn T cells produced IFN-? and IL-17A upon stimulation. T-bet and granzyme B were only weakly expressed by both dn T cell subsets. In conclusion, this study identifies two dn T cell subsets in the dog: (i) a large (~7.5% in Peyer's patches, ~15% in lung) population of TCR??+CD4-CD8?- dn T cells with subpopulations thereof showing an activated phenotype, high expression of FoxP3 or GATA-3 as well as production of IFN-? or IL-17A and (ii) a small TCR??+CD4-CD8?- dn T cell subset also expressing GATA-3 without production of IFN-? or IL-17A. It will be exciting to unravel the function of each subset during immune homeostasis and diseases of dogs.
SUBMITTER: Rabiger FV
PROVIDER: S-EPMC6883510 | biostudies-literature | 2019
REPOSITORIES: biostudies-literature
ACCESS DATA