Oral Abstract Session 01 - Global HIV Vaccine Enterprise

POSTERS
Posters
Topic 8: Mucosal Immunity
P08.13
γδ T-Cells in HIV Infection
N.G. Holt 1 , J. Johnson 1 , S. Wilton 1 , E. Byrne 1 , A. Piechocka-
Trocha 1 , B.D. Walker 2 , D. Kwon 1
1 Ragon Institute of MIT, MGH and Harvard, Boston, MA, USA;
2 Howard Hughes Medical Institute, Chevy Chase, MD, USA
Background: γδ T-cells represent a first line of defense against
pathogens in the mucosa. Despite their prevalence in gut
associated lymphoid tissue (GALT), little is known about their role
in HIV infection. We hypothesize that γδ T-cells are stimulated
by viral antigen and demonstrate anti-HIV activity, comprising a
critical component of the mucosal response to HIV.
Methods: To assess the role of γδ T-cells, we analyzed peripheral
blood and GALT samples from HIV(-) and HIV(+) patients,
including elite controllers. γδ T-cells were isolated and assessed
in viral inhibition and CD4+ killing assays. The cellular pathway
associated with cell killing was also evaluated. An HIV antigen
screen was used to stimulate sorted γδ T-cells. Nanostring
analysis was used to measure mRNA. High-throughput TCR
sequencing was performed in peripheral and mucosal tissue.
Results: The mucosal subtype, Vδ1, exists at higher percentages
in HIV(+) peripheral blood, particularly elite controllers
(17.1±4.0), relative to HIV(-) subjects (0.3±0.2) (p=0.0001). A
100-fold increase of the Vδ1 subtype was detected in the ileum
of HIV controllers. Vδ1 cells in the GALT of HIV(-) patients, unlike
those in the periphery, directly kill up to 80%±20% of HIV+CD4+
T-cells in culture and inhibiting virus production by 3 logs. These
antiviral effects are expanded to the periphery in the setting of
elite control. γδ T-cell mediated killing is correlated to perforin
expression (R=0.8088). Nef-specific responses in Vδ1 cells were
observed in patients with lower viral loads and higher CD4+
count indicating that antiviral effects may be mediated by an HIVspecific
response (p=0.01).
Conclusion: γδ T-cells play a key role in the response to HIV
infection. HIV specific γδ T-cells are expanded from mucosal
tissue to the periphery where they exert anti-viral effects.
Further study may suggest ways to harness this unique subset to
stimulate both innate and acquired immunity in response to HIV.
196
AIDS Vaccine 2012
P08.14
Lack of IgA Envelope-Reactive Antibody Producing
Cells in Terminal Ileum in Early and Chronic HIV-1
Infection
A.M. Trama 1 , H. Liao 1 , A. Foulger 1 , D.J. Marshall 1 , J.F. Whitesides 1 ,
R. Parks 1 , R. Meyerhoff 1 , K.E. Lloyd 1 , M. Donathan 1 , J. Lucas 1 ,
K. Soderberg 1 , T.B. Kepler 2 , N. Vandergrift 1 , N. Yates 1 ,
G.D. Tomaras 1 , M.A. Moody 1 , B.F. Haynes 1
1 Duke University, Durham, NC, USA; 2 Boston University,
Boston, MA, USA
Background: HIV-1 vaccines must induce protective antibodies
at mucosal surfaces; the role of IgA in protection remains
unknown. The HIV-1 Env antibody response begins ~day 17 after
transmission, and derives from a polyreactive memory B cell pool
of gut flora-reactive IgG1 and IgA B cells. Whereas the IgG Env
antibody response persists years after acute HIV-1 infection, the
initial IgA response decreases over the first month. There is also
selective destruction of terminal ileum germinal centers in early
HIV-1 infection (EHI). To determine HIV-1 IgA responses in gut,
we isolated Env-reactive antibodies from ileum from patients in
EHI and chronic HIV-1 infection (CHI).
Methods: Single plasma cells (PCs) and IgD- memory B cells
were sorted from the ileum and/or blood of 7 EHI and 3 CHI.
Antibodies were isolated by PCR amplification of Ig heavy chain
V(D)J and light chain VJ genes and characterized by ELISA and
Luminex.
Results: Whereas CHI blood memory IgA+ B cells reactive with
HIV-1 envelope ranged from 0.20-0.79%, only 0-0.07% of ileum
IgA+ B cells were Env-reactive. Of 254 mAbs isolated from EHI
ileum, only 3 (1.2%) were HIV-1-reactive. In CHI, 9 (5.7%) of
158 mAb were HIV-1 reactive. None of the HIV-1 reactive ileum
antibodies were of the IgA isotype.
Conclusion: HIV-1 envelope reactive IgA+ memory B cells and PCs
can be found in the blood, but there is a dearth of HIV-1 reactive
memory IgA+ B cells and PCs in ileum in EHI and CHI. Loss of IgA in
plasma after acute HIV-1 infection is paralleled by the loss of IgA+
B cells in ileum, and is likely a consequence of HIV-1-induced ileum
germinal center apoptosis. For vaccine design, it will be important
to determine if mucosal IgA+ B cell loss is due to replicating virus
or is triggered by soluble HIV-1 envelope.