CD274 and lymphoma: Co-culturing EBV+ JiJoye lymphoma cells with CD4+ T cells or with peripheral blood mononuclear cells (PBMCs) downregulates CD4+ T cell functions, but the depletion of IRF4 in EBV+ JiJoye lymphoma cells reduces PD1 and PD-L1 expression, and partially restores CD4+ T cell functions.