However, unlike IL-2, IL-15 is not required for the maintenance of Tregs (27); it does not induce activation-induced cell death (AICD) of CD8+ effector T cells (28); is required for the differentiation of NK, effector CD8+ and memory phenotype CD8+ T cells; and does not cause capillary leak syndrome (29). This evidence concerns the gene CD8A and capillary leak syndrome.