It is possible that cytokine milieu required for maturation of CD56-CD16+ neonatal NK cells may not fully develop until after the first year of life, and that HIV infection further compromises production of IL-2, IL-12, and/or IL-15 (Gaddy and Broxmeyer, 1997; Yokoyama et al., 2004; Luevano et al., 2012). This evidence concerns the gene IL2 and HIV infectious disease.