Oral Abstract Session 01 - Global HIV Vaccine Enterprise

Topic 7: Innate Immunity
P07.11
Chronic SIV Infection Induces Differentiation and
Accumulation of Cytotoxic CD16+ NK Cells in Lymph
Nodes Followed by Transmigration to the Mucosae
H. Li 1 , T. Evans 1 , J. Gillis 1 , R. Reeves 1
1 NEPRC, Harvard Medical School, Southborough, MA, USA
Background: Natural killer (NK) cells inhibit lentiviral replication
both directly and indirectly, but substantial evidence also
indicates HIV/SIV can induce NK cell dysfunction. NK cells can
be subdivided based on expression of CD56 and CD16. In blood,
cytotoxic CD16+ NK cells are the dominant subpopulation, while
cytokine-secreting CD56+ and double-negative (DN) NK cells are
the primary NK cells found in lymph nodes (LN). Furthermore,
CD56+ and DN NK are thought to be precursor populations,
whereas CD16+ NK cells are terminally differentiated. The effects
of HIV/SIV infection on NK cell distribution, trafficking, and
development are unclear.
Methods: Macaque NK cells were isolated from blood, LN, and
mucosal tissues of naive and chronically SIV-infected animals and
then analyzed phenotypically by surface and intracellular flow
cytometry, evaluated functionally by ICS and in a direct killing
assay against MHC-devoid 721.221 cells. In situ analyses were
performed by immunohistochemistry.
Results: In peripheral blood of chronically infected animals,
we found a specific expansion of CD16+ NK cells, coupled
with high frequencies of cytotoxic perforin+ CD16+ NK cells in
LN, where they are normally absent. Interestingly, classic LNtrafficking
molecules, CD62L and CCR7, were downregulated to
undetectable levels on blood and LN CD16+ NK cells, suggesting
they did not migrate from extralymphoid tissues. Furthermore,
the putative NK cell precursors, CD56+ and DN NK cells, exhibited
increased proliferation and activation, providing a potential
source of differentiated CD16+ NK cells. CD16+ NK cells in LN also
upregulated the mucosa-trafficking marker, α4β7, correlating
with increased frequencies of cytotoxic CD16+ NK cells in
colorectal and jejunum tissues of infected animals.
Conclusion: Our data suggest a novel mechanism whereby
lentivirus infection induces differentiation of cytotoxic CD16+
NK cells, which are normally absent in LN, to differentiate in
situ and then transmigrate to the gut mucosa, the primary site
of virus replication.
P07.12
AIDS Vaccine 2012
Posters
HIV-1 p24 Derived Epitopes Modulate KIR2DL2-
Binding to HLA-Cw03
N.H. van Teijlingen 1 , C. Körner 2 , L. Fadda 2 , C. Brander 3 ,
M.N. Carrington 4 , D. van Baarle 1 , M. Altfeld 2
1 UMC Utrecht, Utrecht, Netherlands; 2 Ragon Institute of
MGH, MIT and Harvard, Boston, MA, USA; 3 IrsiCaixa (Institut
de Recerca de la Sida), Barcelona, Spain; 4 National Cancer
Institute at Frederick, Frederick, MD, USA
Background: Recent studies have suggested that HIV-1 can
evade Natural Killer (NK)-cell-mediated immunity by mutating
viral epitopes to enhance engagement of inhibitory Killer Ig-like
receptors (KIRs) expressed on NK cells. However, the precise
mechanisms modulating the interaction of inhibitory KIRs and
their HLA class I ligands, and the role that HIV-1 epitopes might
play in this interaction are not well understood. In this study
we investigated whether HLA-Cw3-presented epitopes within
HIV-1 p24 Gag can modulate binding of KIR2DL2, an inhibitory
KIR, to HLA-Cw03.
Methods: Using tapasin-deficient 721.220 cell line expressing
HLA-Cw*0304 we initially screened for HIV-1 peptides that
stabilized HLA-Cw*0304 expression using 222 10-mer peptides
overlapping by 9 amino acids spanning the entire HIV-1 p24 Gag
sequence. Peptides stabalizing HLA-Cw*0304 expression were
thereafter investigated for their ability to facilitate binding of a
KIR2DL2-IgG fusion construct.
Results: We identified several HIV-1 p24 epitopes that were
able to stabilize HLA–Cw*0304 expression. A subset of these
epitopes also allowed for binding of KIR2DL2. Currently we are
investigating the consequences of KIR2DL2-binding to HLA class I
presented HIV-1 epitopes for the antiviral function of primary NK
cells from KIR2DL2+ individuals.
Conclusion: Taken together, these studies have identified
epitopes within HIV-1 that enhance the binding of the inhibitory
NK cell receptor KIR2DL2 to its ligand HLA-Cw3, and are in line
with recent data suggesting that the sequence of the HLA class
I presented epitope has an important impact on the interaction
between KIR and HLA class I (Boyington et al. Nature 2000, Vivian
et al. Nature 2011).
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POSTERS