Although CD4+ T cell help is critical for sustained CD8+ T cell cytotoxic function during chronic LCMV infection (158), other studies showed that combining PD-L blockade with CD4+ T cell depletion (159) or Treg cell depletion (160) could rescue deeply exhausted CD8+ T cells during the late stage of infection and may result in a significant reduction in viral load. The gene discussed is CD8A; the disease is infection.