IRF4 and infection: Consistently, the RT-qPCR results show that LMP1, IRF4, and PD-L1 were all significantly higher in PBMCs without CD4+ T cells 17 days post-infection (Figure 4C), and proliferating colonies were significantly more grown from PBMCs depleted of CD4 T cells compared with intact PBMCs by day 26 post-infection (Figure 4D).