Flow Cytometry Analysis of Surface PD-L1 Expression Induced by IFNγ and Romidepsin in Ovarian Cancer Cells

Expression of programmed death ligand-1 (PD-L1, CD274) on cancer cells is regulated by interferon-γ (IFNγ) signaling as well as by epigenetic mechanisms. By binding to PD-1 on cytotoxic T cells, PD-L1 inhibits T cell-mediated antitumor responses, resulting in immune escape. This chapter describes analysis of the surface PD-L1 expression in ovarian cancer (OC) cells using flow cytometry (FC). Our data demonstrate that the surface PD-L1 expression in OC cells is induced by IFNγ as well as by the class I histone deacetylase (HDAC) inhibition by romidepsin, suggesting that class I HDAC inhibition might provide a useful strategy to modulate the PD-L1 levels on OC cells.