Human leukocyte antigen (HLA) B*27 and B*57 are associated with protection against HIV-1 disease progression, yet most persons expressing these alleles are unable to control HIV-1. Here we show that HLA-B*27-restricted CD8+ T cells in controllers and progressors differ in their ability to inhibit virus replication through targeting of the immunodominant Gag epitope. This is associated with distinct TCR clonotypes, characterized by superior control of HIV-1 replication in vitro, greater cross-reactivity against epitope variants, and enhanced perforin delivery. Clonotype-specific differences in antiviral efficacy were also observed for an immunodominant HLA-B*57 restricted response in controllers and progressors. Thus, the efficacy of protective alleles is modulated by specific TCR clonotypes selected in natural infection, providing a functional explanation for divergent HIV-1 outcomes.

Analyses of the breadth and specificity of virus-specific CD8؉ T cell responses associated with control of HIV have largely relied on measurement of cytokine secretion by effector T cells. These have resulted in the identification of HIV elite controllers with low or absent responses in which non-T-cell mechanisms of control have been suggested. However, successful control of HIV infection may be associated with central memory T cells, which have not been consistently examined in these individuals. Gagspecific T cells were characterized using a peptide-based cultured enzyme-linked immunosorbent spot assay (ELISpot). Peripheral blood mononuclear cells from HIV elite controllers (n ‫؍‬ 10), progressors (n ‫؍‬ 12), and antiretroviral-treated individuals (n ‫؍‬ 9) were cultured with overlapping peptides for 12 days. Specificity was assessed by tetramer staining, functional features of expanded cells were assessed by cytokine secretion, and virus inhibition and phenotypic characteristics were assessed by cell sorting and coculture assays. After peptide stimulation, elite controllers showed a greater number of previously undetectable (new) responses compared to progressors (P ‫؍‬ 0.0008). These responses were highly polyfunctional, with 64.5% of responses having 3 to 5 functions. Expandable epitope-specific CD8 ؉ T cells from elite controllers had strong virus inhibitory capacity and predominantly displayed a central memory phenotype. These data indicate that elite controllers with minimal T cell responses harbor a highly functional, broadly directed central memory T cell population that is capable of suppressing HIV in vitro. Comprehensive examination of this cell population could provide insight into the immune responses associated with successful containment of viremia.

• Immune monitoring models integrating multiple functions of HIV-1-specific CD8 T cells distinguish controllers from subjects with progressive HIV-1 infection.• This strategy may have important applications in predictive model development and immune monitoring of HIV-1 vaccine trials.

SUMMARY Decreased human immunodeficiency virus (HIV)-specific CD8+ T cell proliferation is a hallmark of chronic infection, but the mechanisms of decline are unclear. We analyzed gene expression profiles from antigen-stimulated HIV-specific CD8+ T cells from patients with controlled and uncontrolled infection and identified caspase-8 as a correlate of dysfunctional CD8+ T cell proliferation. Caspase-8 activity was upregulated in HIV-specific CD8+ T cells from progressors and correlated positively with disease progression and programmed cell death-1 (PD-1) expression, but negatively with proliferation. In addition, progressor cells displayed a decreased ability to upregulate membrane-associated caspase-8 activity and increased necrotic cell death following antigenic stimulation, implicating the programmed cell death pathway necroptosis. In vitro necroptosis blockade rescued HIV-specific CD8+ T cell proliferation in progressors, as did silencing of necroptosis mediator RIPK3. Thus, chronic stimulation leading to upregulated caspase-8 activity contributes to dysfunctional HIV-specific CD8+ T cell proliferation through activation of necroptosis and increased cell death.