CD2 and CD8α define porcine γδ T cells with distinct cytokine production profiles

• Only CD2− γδ T cells with a rare CD8α+CD27− phenotype produced IL-17A.
• Within CD2+ γδ T cells IFN-γ producing cells strongly dominated.
• IFN-γ/TNF-α co-producing γδ T cells had a distinct CD2+CD8α+CD27− phenotype.
• CD2 and CD8α expression correlates with distinct cytokine production profiles.

γδ 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− γδ T cells in their vast majority had a CD8α−SLA-DR−CD27+ phenotype. CD2+ γδ T cells dominated in spleen and lymph nodes and had a more heterogeneous phenotype. CD8α+SLA-DR−CD27+ γδ T cells prevailed in blood, spleen and lymph nodes whereas in liver a CD8α+SLA-DR+CD27− phenotype dominated, indicating an enrichment of terminally differentiated γδ T cells. γδ T cells were also investigated for their potential to produce IFN-γ, TNF-α and IL-17A. Within CD2+ γδ T cells, IFN-γ and TNF-α single-producers as well as IFN-γ/TNF-α double-producers dominated, which had a CD8α+CD27+/− phenotype. IL-17A-producing γδ T cells were only found within CD2− γδ T cells, mostly co-produced TNF-α and had a rare CD8α+CD27− phenotype. However, quantitatively TNF-α single-producers strongly dominated within CD2− γδ T cells. In summary, our data identify CD2 and CD8α as important molecules correlating with functional differentiation.