CD274 and neoplasm: Immunohistochemistry on paraffin-embedded diagnostic tissue samples [15] and multi-parameter flow cytometry on pleural fluids (vide Materials and methods) was assessed for the presence of CD4+ and CD8+ T cells and macrophages and the expression of PD-L1 on tumor cells and PD-L1, LAG-3 and TIM-3 on lymphocytes.