Bovine luteal cells elicit major histocompatibility complex class II- dependent T-cell proliferation

Major histocompatibility complex (MHC) class II molecules are expressed in the bovine corpus luteum (CL) in a manner correlating with luteolysis. Whether bovine luteal cells can stimulate T-cell proliferation in a class II- restricted manner was investigated. Staphylococcal enterotoxin B (SEB) enhances T-cell proliferation by a mechanism requiring MHC class II molecules and was used to examine stimulation of T-cell proliferation by luteal cells. Luteal cells from midcycle or regressing CL (induced by prostaglandin F(2α)) were cocultured with autologous T cells in the presence of no treatment, SEB (1 μg/ml), or SEB + anti-MHC class II antibody (3 μg/ml); and proliferation was assessed by incorporation of tritiated thymidine. T cells proliferated in the presence of cells from regressing CL more than when in the presence of midcycle cells (118 309 ± 20.567 vs. 75 261 ± 12 494 cpm; p < 0.05). Anti- MHC attenuated this response of cells from regressing CL (81 108 cpm ± 13 249; p < 0.05). Without SEB, T cells proliferated when cultured with cells from regressing, but not midcycle, CL (4637 ± 816 vs. 2117 ± 589 cpm; p < 0.03). These results suggest that luteal cells can function as antigen- presenting cells in vitro and that prostaglandin F(2α) may enhance their ability to present antigen.