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Cutting Edge: T Regulatory Cell Depletion Reactivates Latent Simian Immunodeficiency Virus (SIV) in Controller Macaques While Boosting SIV-Specific T Lymphocytes

2016; American Association of Immunologists; Volume: 197; Issue: 12 Linguagem: Inglês

10.4049/jimmunol.1601539

1550-6606

Tianyu He, Egidio Brocca‐Cofano, Benjamin B. Policicchio, Ranjit Sivanandham, Rajeev Gautam, Kevin D. Raehtz, Cuiling Xu, Ivona Pandrea, Cristian Apetrei,

Immune responses and vaccinations

T regulatory cells (Tregs) are critical in shaping the latent HIV/SIV reservoir, as they are preferentially infected, reverse CD4+ T cell activation status, and suppress CTL responses. To reactivate latent virus and boost cell-mediated immune responses, we performed in vivo Treg depletion with Ontak (denileukin diftitox) in two SIVsab-infected controller macaques. Ontak induced significant (>75%) Treg depletion and major CD4+ T cell activation, and only minimally depleted CD8+ T cells. The overall ability of Tregs to control immune responses was significantly impaired despite their incomplete depletion, resulting in both reactivation of latent virus (virus rebound to 103 viral RNA copies/ml plasma in the absence of antiretroviral therapy) and a significant boost of SIV-specific CD8+ T cell frequency, with rapid clearance of reactivated virus. As none of the latency-reversing agents in development have such dual activity, our strategy holds great promise for cure research.