Figure 6.

Neuronal PD-L1 binds an unknown receptor on gliomas for apoptotic function. A, Immunostaining of in vitro cultured GL261 cells with isotype control, PD-L1 (Cy3-red), or B7.1 (FITC) and Hoechst. Scale bar, 25 μm. B, FACS for PD-1, PD-L1, and B7.1 in cultured GL261 cells. Red line, isotype controls. Data are representative of three independent experiments. C, Western blot of PD-1 and B7.1 proteins in GL261 cells. D, Analysis of percentage of dead GL261 cells using FACS for 7AAD of GL261 cells alone or after coculture with 3 DIV CGNs. Blocking antibodies or fusion protein (20 μg/ml) were used before coculturing unless indicated. Data are mean ± SD from three individual experiments; ***p < 0.001.