Luteal cells from functional and regressing bovine corpora lutea differentially alter the function of gamma delta T cells

The luteal microenvironment is thought to direct the function of resident immune cells to facilitate either luteal function or regression. To determine if luteal cells from functional (Days 10- 12) and regressing (8 h after administration of prostaglandin F_2alpha) corpora lutea (CL) induce different responses in γδ T cells, luteal cells were cocultured with autologous γδ T cells isolated from peripheral blood. Proliferation, functional phenotypes, and cytokine synthesis were analyzed by flow cytometry. To determine if the luteal cells from functional CL induce hyporesponsiveness in γδ T cells, γδ⁺ cells were cocultured with midcycle luteal cells and further stimulated with concanavalin A. Coculture of γδ⁺ cells with midcycle luteal cells did not inhibit concanavalin A-induced proliferation. In a proliferation assay, luteal cells from midcycle CL predominantly induced proliferation of γδ⁺ WC1^- cells (P<0.05), while luteal cells from regressing CL predominantly induced proliferation of γδ⁺WC1⁺ cells (P<0.05). Analysis of intracellular cytokines indicated that midcycle luteal cells increased the proportion of γδ⁺ cells containing interleukin 10 (P<0.05), but reduced the proportion of γδ⁺ cells containing interferon gamma (IFNG; P<0.05). There were no changes in the proportions of γδ⁺ cells synthesizing interleukin 4 or tumor necrosis factor. Unexpectedly, coculture of γδ⁺ cells with luteal cells from regressing CL had no effect on any of the cytokines analyzed. These data support the hypothesis that the function of resident T cells is differentially modulated depending on the status of the CL.