CROI 2017 Abstract e-Book

Abstract eBook

Poster and Themed Discussion Abstracts

capacity was maintained over time, was also observed at lower E:T ratios and was confirmed with 2 clade B viruses. Suppressive activity was not associated with levels of PD-1 and HLA-DR expression on total CD4 and CD8 T cells or total HIV-specific response at any time-point assessed. Conclusion: Early initiation of ART was associated with preservation of functional HIV-specific T cell responses. Although CD8+ T-cell mediated antiviral inhibitory activity was higher in early-treated than chronic cART individuals, levels were inferior to those reported in HIV controllers. This suggests that although early treatment was able to preserve CD8+ T cell antiviral functional capacity for at least one year, it was not able to completely prevent immune activation and T cell exhaustion. 272 WITHDRAWN 273 TRAIL-SHORT REDUCES THE CYTOTOXIC CAPACITY OF NK CELLS Fatma Aboulnasr , Nathan Cummins, Zilin Nie, Stephen Burke, Andrew Badley Mayo Clinic, Rochester, MN, USA Background: TRAIL-short (TRAIL-s) is a novel splice variant of TRAIL, capable of blocking TRAIL mediated cell death. Previous studies from our lab have shown that the plasma concentration of TRAIL-s in HIV infected patients correlates with viral load and increases cell resistance to TRAIL-induced death. Natural killer (NK) cells play a key role in the antiviral response to HIV infection. While NK cells can produce TRAIL as an effector molecule to kill tumor cells, its role in antiviral defense is just emerging. In the current study we sought to determine the effect of TRAIL-s on NK function. Methods: Jurkat cells were transfected with a control or TRAIL-short expressing plasmids, and incubated with primary NK cells from uninfected donors (N=10) at various Effector :Target ratios (1:1 to 20:1). A flow cytometric-based assay was used to determine the cytotoxic effects of the NK cells on the target Jurkat cells. The effect of TRAIL-s overexpression on NK cell activity and function was determined by staining for CD69, Perforin, CD16 and CD107a. In addition the effect of HIV IIIB- gp120, or supernatant containing HIV IIIB virus on NK expression of TRAIL and TRAIL-s was measured by surface staining. Results: Overexpression of TRAIL-s in target cells significantly reduced the cytotoxic function of NK against these cells across a range of E:T ratios compared to the control cells (p=0.006 at an E:T ratio of 20:1).However this overexpression did not alter the expression of CD 69, CD16, Perforin or CD107a in NK cells. Interestingly pre-treatment of NK cells with culture supernatant containing HIV IIIB virus caused a large increase in surface expression of TRAIL-s, yet had no effect on TRAIL expression, whereas gp120 alone did not. Conclusion: TRAIL-s expression significantly reduces NK mediated cytotoxicity. HIV containing supernatant alone increases the surface expression of TRAILs on NK cells. This provides new insight to the effect of TRAIL-s on NK function, and argues that blockade of TRAIL-s, may increase NK cytotoxicity against virally infected cells. 274 OF THE TB01 MOTIF KIR GENES, KIR3DS1 PLAYS ROLE IN HIV RESISTANCE & NK CELL FUNCTION Zahra Kiani 1 , Elise Jackson 1 , Xin Yu Zhang 1 , Irene Lisovsky 1 , Benjamin Tallon 1 , Julie Bruneau 2 , Jean-Pierre Routy 3 , Nicole Bernard 4 1 McGill Univ, Montreal, Quebec, 2 Univ of Montreal, Montreal, Canada, 3 McGill Univ Hlth Cntr, Glen site, Montréal, Canada, 4 Rsr Inst, McGill Univ Hlth Cntr, Montreal, Canada Background: Some individuals, called HIV exposed seronegative (HESN), remain HIV uninfected despite repeated HIV exposures. Studying HESN improves our understanding of the mechanisms underlying resistance to HIV infection. Previous work by our group found that KIR3DS1 (3DS1) homozygotes (hmz) were more frequent among HESN than HIV+ subjects. 3DS1 is in linkage disequilibriumwith other KIR genes in the telomeric KIR B region known as the TB01 motif. The TB01 motif is characterized by the presence of 3DS1 and KIR2DL5A (2DL5A) genes and the absence of a KIR2DS4 (2DS4) locus. Here, we probed the contribution of TB01 motif KIR genes to NK cell functionality. Methods: We compared the frequency of linked 3DS1, 2DL5A and 2DS4 genes in 105 HESN and 414 HIV+ subjects. To address the contribution of 3DS1 and 2DL5 to NK cell functionality we examined the responses of 3DS1+/-/2DL5+/- NK cells from 8 subjects who were 3DS1hmz and 2DL5A+ to stimulation by the HLA-null cell line 721.221 (221). Responsiveness was measured by assessing the % of 3DS1+/-/2DL5+/- NK cells secreting IFN-γ and CCL4 and expressing CD107a. Results: HESN. compared to HIV+ subjects, were more frequently 3DS1hmz, trended towards being more frequently 2DL5A+ and less frequently carried an expressed 2DS4 allele. Carriage of a TB01 motif and being TB01 homozygous were more frequent in HESN than HIV+ subjects (Fisher’s exact tests). 221 cells stimulated a higher frequency of functional 3DS1+ than 3DS1- NK cells while expression of 2DL5A either with 3DS1 or alone did not further contribute to the frequency of HLA-null responsive cells (Friedman and Wilcoxon tests). Conclusion: The linkage disequilibrium present among KIR genes in the TB01 KIR region confounds ascribing a role in protection from infection to one or more of these linked genes. The stochastic expression of KIR gene products on NK cells allowed us to show that 3DS1 confers functionality to NK cells populations expressing this gene product while 2DL5A does not. 3DS1 may confer functionality by interacting with HLA-F on 221 cells to transmit activating signals to 3DS1+ NK cells. The role of other TB01 KIR gene products has not been entirely eliminated but The TB01 motif lacks a 2DS4 gene and the KIR2DS3 gene in this motif encodes poorly expressed receptors. Together, these results point towards 3DS1 being a gene product important in conferring NK cell functionality associated with protection from HIV infection in HESN. 275 NO RECOVERY OF VΑ7.2 MAIT CELLS AFTER THERAPEUTIC IMMUNISATION PLUS IL-2/GM-CSF/RHGH Louise Greathead , Alexander Cocker, Anna Herasimtschuk, Sundhiya Mandalia, Peter Kelleher, Nesrina Imami Imperial Coll London, London, UK Background: Mucosal-associated invariant T (MAIT) cells are lost in HIV-1 infection and do not recover on antiretroviral therapy (ART). Therapeutic immunisation (GTU-MultiHIV Clade B DNA vaccine) together with interleukin-2 (IL-2), granulocyte-macrophage colony-stimulating factor (GM-CSF) and recombinant human growth hormone (rhGH), has been shown to reduce immune activation and improve HIV-1-specific T-cell responses in ART-treated HIV-1 infected individuals. In this study we assessed the ability of this regimen to reconstitute MAIT cell populations. Methods: Flow cytometry was performed on cryopreserved peripheral blood mononuclear cells taken from 12 patients at baseline, week 2 and week 48. Participants were randomised into one of three groups: 1) vaccine plus IL-2, GM-CSF and rhGH (n=3); 2) vaccine alone (n=4); or 3) IL-2, GM-CSF and rhGH alone (n=5). MAIT cells were identified as live CD3+CD45RO+ T cells co-expressing the invariant T cell receptor Vα7.2 together with the C-type lectin CD161. CD4 and CD8 memory T cell expression of CD38 was used as a marker of T-cell activation. Wilcoxon matched-pairs signed rank test and longitudinal MIXED method analysis were used to evaluate changes from baseline to week 2 and week 48. Correlations were performed using Spearman’s Rho. Results: The ratio of CD4/CD8 memory T cells rose significantly at week 2 (p=0.002) and was maintained at week 48 (p=0.005) compared to baseline in the combined group of patients. CD4 and CD8 T cell activation (CD38+) also significantly rose at week 2. There was a significant fall of CD8 T cell activation at week 48 compared to baseline (p=0.021) in the combined group. Baseline MAIT cell frequency was 1.49% (0.49-2.96) of CD3 memory T cells in the combined group. MAIT cell frequency fell to 0.85% (0.46-1.71, p=0.021) at week 2 before rising to 1.32% (0.57-2.64) at week 48 in the combined group. There was no significant change in MAIT cell frequency at week 48 in patients randomised to receive IL-2/GM-CSF and rhGH, either with (group 1) or without (group 3) vaccine. There were no correlations between baseline or week 48 MAIT cell frequencies and T-cell activation. Conclusion: Peripheral blood MAIT cells fail to reconstitute following successful ART combined with therapeutic immunisation and IL-2, GM-CSF and rhGH administration. 276 REDUCED CD161 EXPRESSION ON MAIT CELLS IN HIV-INFECTED SUBJECTS WITH IMMUNE FAILURE

Poster and Themed Discussion Abstracts

Michael L. Freeman , Michael M. Lederman Case Western Reserve Univ, Cleveland, OH, USA

Background: Mucosa-associated invariant T (MAIT) cells are a recently identified class of innate-like T cells that are involved in the mucosal immune response. MAIT cells are characterized by expression of TCR Vα7.2 and CD161. In HIV infection there is a profound early loss of MAIT cells from the circulation that never fully recovers, even after prolonged

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