CD4 and AIDS: This WHO review was necessitated by studies which showed that initiating ART at a CD4+ cell count > 350cells/ul compared with treatment at a CD4+ cell count ≤ 350cells/ul reduced the risk of progression to AIDS and/or death[2], reduced the risk of development of tuberculosis (TB)[3][4] and non-AIDS-defining illness[2], as well as increased the likelihood of immune recovery[2][5].