CD4 and neoplasm: Moreover, research has shown that ZnO can be constructed as mesoporous ZnO nanocapsules, antigen-absorbed ZnO tetrapod nanoparticles, or Zn-doped mesoporous silica NPs, which can all boost the tumor immunity cycle by strengthening cytotoxic T lymphocyte (CTL) activity and enhancing levels of IFN-γ-producing CD4+ and CD8+ T cells [71,72,73].