Time course of miR-34a and PD-L1 and PD-L2 protein expression in the EBV model. (A) miR-34a was serially quantified by qRT-PCR (relative to the 8-hour time point) during the EBV model. (B) PD-L1 and PD-L2 protein expression on CD20⁺ B cells during the time course of the EBV model of B-cell differentiation. After EBV WIL infection, PD-L1 and PD-L2 protein expression, measured by flow cytometry, rises, coincident with transition from the late GCB to early ABC phase. From 3 weeks onward, levels of PD-L1 and PD-L2 are maintained at stable levels (data not shown).