CD4 and idiopathic CD4 lymphocytopenia: Microbial translocation is characteristic of the disease pathogenesis of not only acquired immunodeficiency (HIV infection) (136) but also primary deficiencies, such as idiopathic CD4+ T-cell lymphocytopenia (ICL) (137); however, the link between microbial translocation and the perturbation of CD4+ T cell homeostasis in ICL is not as obvious as in the case of HIV-1/AIDS.