CD2 and CD8 alpha define porcine gamma delta T cells with distinct cytokine production profiles

gamma delta T cells are a remarkably prominent T-cell subset in swine with a high prevalence in blood. Phenotypic analyses in this study showed that CD2 super(-) gamma delta T cells in their vast majority had a CD8 alpha super(-)SLA-DR super(-)CD27 super(+) phenotype. CD2 super(+) gamma delta T cells dominated in spleen and lymph nodes and had a more heterogeneous phenotype. CD8 alpha super(+)SLA-DR super(-)CD27 super(+) gamma delta T cells prevailed in blood, spleen and lymph nodes whereas in liver a CD8 alpha super(+)SLA-DR super(+)CD27 super(-) phenotype dominated, indicating an enrichment of terminally differentiated gamma delta T cells. gamma delta T cells were also investigated for their potential to produce IFN- gamma , TNF- alpha and IL-17A. Within CD2 super(+) gamma delta T cells, IFN- gamma and TNF- alpha single-producers as well as IFN- gamma /TNF- alpha double-producers dominated, which had a CD8 alpha super(+)CD27 super(+/-) phenotype. IL-17A-producing gamma delta T cells were only found within CD2 super(-) gamma delta T cells, mostly co-produced TNF- alpha and had a rare CD8 alpha super(+)CD27 super(-) phenotype. However, quantitatively TNF- alpha single-producers strongly dominated within CD2 super(-) gamma delta T cells. In summary, our data identify CD2 and CD8 alpha as important molecules correlating with functional differentiation.