The Role of Natural Killer (NK) Cells and NK Cell Receptor Polymorphisms in the Assessment of HIV-1 Neutralization

Abstract

The importance of innate immune cells in HIV-1 pathogenesis and protection has been highlighted by the role of natural killer (NK) cells in the containment of viral replication. Use of peripheral blood mononuclear cells (PBMC) in immunologic studies provides both HIV-1 target cells (ie. CD4+ T cells), as well as anti-HIV-1 effector cells, such as NK cells. In this study, NK and other immune cell populations were analyzed in HIV-negative donor PBMC for an impact on the anti-HIV activity of polyclonal and monoclonal antibodies. NK cell percentages were significantly higher in donor PBMC that supported lower levels of viral replication. While the percentage of NK cells was not directly associated with neutralization titers, NK cell-depletion significantly diminished the antiviral antibody activity by up to three logs, and polymorphisms in NK killer immunoglobulin receptor (KIR) and FcγRIIIa alleles appear to be associated with this affect. These findings demonstrate that NK cells and NK cell receptor polymorphisms may influence assessment of traditional HIV-1 neutralization in a platform where antibody is continuously present. This format appears to simultaneously assess conventional entry inhibition (neutralization) and non-neutralizing antibody-dependent HIV inhibition, which may provide the opportunity to delineate the dominant antibody function(s) in polyclonal vaccine responses.

In Vivo Activation of Human NK Cells by Treatment with an Interleukin-15 Superagonist Potently Inhibits Acute In Vivo HIV-1 Infection in Humanized Mice

“…As the infectious inoculum, we used HIV-LucR, a replication-competent molecular HIV clone expressing the HIV-1 JR-CSF Env protein and a Renilla luciferase reporter gene, which enables HIV-1 infection to be quantified by directly measuring the luciferase activity of infected cells (21). HIV-LucR has been well established as an infectious inoculum that can be used to evaluate the capacity of antibodies, NK cells, and CD8 T cells to inhibit HIV-1 infection (35)(36)(37)(38)(39)(40)(41)(42). One day after hu-spl-PBMC-NSG mice were infected with HIV-1 by intrasplenic injection with HIV-LucR, one group of mice was intravenously injected with a dose of the IL-15 superagonist.…”

Tenascin-C is an innate broad-spectrum, HIV-1–neutralizing protein in breast milk

“…For virus neutralization assays, purified protein and milk samples were incubated with 293T cell-produced HIV-1 infectious molecular clones (CH40, CH77, CH58, CM235), or HIV-1 Env pseudoviruses (all other variants) were tested for neutralization potency in TZM-bl target cells (19,20). Additionally, an HIV-1 infectious molecular clone (NL-LucR.T2A-CH040.ecto) (59) produced in human PBMCs was incubated with purified TNC and tested for neutralization in activated human PBMCs (60,61). For determining the interaction between TNC and breast milk HIV-neutralizing antibodies, HIV MW965 virions were incubated for 1 h with either the colostrum HIV-neutralizing mAb CH08 (39), TNC (final concentration 175 μg/mL), or CH08 and TNC, and then TZM-bl cells were added.…”

Functions of Antibodies

“…Modulation of inflammation is another FcR-mediated antibody function that can impact several pathogens (160,161,162,163,164). Finally, studies have documented the impact of FcR engagement on assays used to measure the neutralizing activity of antibodies (165,166,167,168).…”