IL-21 and IFNalpha therapy rescues terminally-differentiated NK cells and limit SIV reservoir in ART-treated macaques [cohort1]

Unlike HIV infection, which progresses to AIDS absent suppressive anti-retroviral therapy (ART), nonpathogenic infections in natural hosts, such African green monkeys (AGMs), are characterized by a lack of gut microbial translocation and robust secondary lymphoid Natural Killer (NK) cell responses resulting in absence of chronic inflammation and limited SIV dissemination in lymph nodes (LN) B-cell-follicles, respectively. In a pathogenic infection model (i.e. ART-treated, SIVmac239-infected rhesus macaques; RMs), sequential Interleukin (IL)-21 and interferon (IFN)-alpha therapy generated terminally-differentiated blood NK cells (NKG2a/clowCD16+) with potent HLA-E-restricted activity in response to SIV-ENV peptides in contrast to control RMs, where less differentiated, IFN-gamma+ NK cells predominated. The frequency and cytolytic activity of NKG2a/clowCD16+ NK cells correlated with a reduction of replication-competent SIV in LN during ART and viral rebound delay following analytical treatment interruption. These data demonstrate that AGM-like NK cell differentiation profiles can be rescued in RMs to promote viral clearance in tissues. 11 SIV infected and ART-treated rhesus macaques were used. 6 were treated with IL-21 and IFN-alpha and 5 were untreated controls.