The virtual absence of CD4+ cells in the oral mucosa of HIV-infected patients with the erythematous or pseudomembranous forms of OPC [6,7,8], as well as lower tissue densities of this cell population in HIV-positive compared to HIV-negative controls without OPC [6], further suggested a role for CD4+ cell depletion in the immunopathogenesis of OPC in the setting of HIV/AIDS. This evidence concerns the gene CD4 and AIDS.