CD4 and AIDS: CD4+TRM cells and tissue-resident macrophages are the main reservoirs of persistent HIV infection, which support HIV replication and the progression toward AIDS.515–519 Adipose tissue has been recognized as the latent location for HIV infection.520 Staying in HIV-infected subcutaneous adipose tissues, Treg cells and PD-1+CD4+TRM cells construct an immunomodulatory milieu that protects HIV persistence.521