IL-12 and IL-18 induce interferon-γ production and de novo CD2 expression in porcine γδ T cells

• After IL-2/IL-12/IL-18 stimulation CD2+ γδ T cells produced highest levels of IFN-γ.
• CD2+ γδ T cells showed highest proliferation after ConA/IL-2/IL-12/IL-18 stimulation.
• CD2− γδ T cells showed CD2 de novo expression after ConA/IL-2/IL-12/IL-18 stimulation.

γδ T cells are highly abundant in the blood and spleen of pigs but little is known about their functional differentiation. In this study the potential of the type-1 polarizing cytokines IL-12 and IL-18 in combination with IL-2 and Concanavalin A (ConA) to stimulate porcine γδ T cells was investigated. Stimulation of purified γδ T cells with ConA and IL-2 induced a strong proliferation of CD2− γδ T cells, whereas additional stimulation with IL-12 and IL-18 caused a stronger proliferation of CD2+ γδ T cells. IFN-γ could only be detected in supernatants of γδ T-cell cultures supplemented with IL-12 and IL-18. Experiments with sorted CD2/SWC5-defined γδ T-cell subsets revealed that CD2+SWC5− γδ T cells are the main producers of IFN-γ following stimulation with IL-2/IL-12/IL-18. Additional stimulation with ConA led to an upregulation of CD2 within the CD2− γδ T cell subsets, indicating a previously unnoticed plasticity of CD2-defined γδ T cell subsets.