Abstract Book Vol. 2 [International Conference on AIDS (14th: 2002: Barcelona, Spain)]

XIV International AIDS Conference

Abstracts ThPeA7132-ThPeA7135 367

R5 viruses, was inhibited by Tc cells from the HIV-seropositive individual but only
rarely by CD8+ clones from the seronegative donor.
Conclusions: The data demonstrated that the three CD8+ T cell subsets TcO,
Tc1 and Tc2 could control equally X4 virus replication but the inhibition of R5
virus replication is rather a characteristic of the different Tc subsets from infected
individuals.
Presenting author: Michele Fevrier, Institut Pasteur, LIPV, 25 rue du Dr Roux,
75015 Paris, France, Tel.: [phone], E-mail: [email protected]
ThPeA7132 Lysis of monocyte-derived dendritic cells by
autologous natural killer cells in patients with early
hiv-1 infection
C. Fortis, S. Tasca, B. Capiluppi, A. Lazzarin, G. Tambussi. San Raffaele
Scientific Institute, Milano, Italy
Background: monocyte-derived dendritic cells (MDDC) may be infected by HIV1. Recently, it has been reported that they may be lysed by autologous NK cells.
NK cells provide a first line of defence against viral infections, and their activity is
compromised in HIV-infected patients. We evaluated NK cell lytic activity vs autologous MDDC, and in parallel vs K562 cell line (a classical target of NK cells)
in 11 pts with early HIV infection (<6 months from infection), in 2 pts with primary
HIV infection (PHI), and in 8 normal subjects as a control group.
Methods: PBMC were obtained over Ficoll gradient and plated for 2 hrs on 24 -well plates. After washing to remove non-adherent cells, adherent cells were stimulated with GM-CSF + IL-4 for 6-10 days to induce immature MDDC, while nonadherent cells were stimulated with IL-2 to activate NK cells. The lytic potential
of activated NK cells was tested in a standard 4-h [51Cr]-release assay using as
target cells autologous MDDC and K562 cells.
Results: respect to the lysis of MDDC, HIV-infected pts were divided in two distinct groups: 8 pts had values comparables to those observed in normal subjects
while 5 pts had nearly absent lysis. Six aut of 8 pts with normal lytic activity had
significantly higher circulating CD4+ T cells, and lower CD8+ T cells and viral load
(VL) respect to the 5 pts with no lytic activity. The only two pts with normal lytic activity, but high VL were PHI pts. Exogenous HIV-Tat protein significantly reduced
the lysis of MDDC. All pts had a NK cell lytic activity vs K562 target comparable
to that observed in the control group.
Conclusions: in early HIV-infected pts, but not in PHI pts, the control of viral
replication seems to depend on a conserved NK cell activity against autologous
MDDC. The release of Tat protein from infected cells might represent a mechanism of virus escape from the control of natural immunity.
Presenting author: Claudio Fortis, San Raffaele Scientific Institute, Via Stamira
d'Ancona, 20, 20127 Milano, Italy, Tel.: [phone], Fax: [phone],
E-mail: [email protected]
ThPeA7133 Lack of Vy9V82 T cell effectors in
immunocompromised hosts and rapid y8 T cell
impairment during Structured Treatment
Interruption
F. Martini, C. Agrati, D. Goletti, D. Vincenti, S. Carrara, C. Gioia, G. D'Offizi,
G. Ippolito, L.P. Pucillo, F. Poccia, C. Montesano. National Institute for Infectious
Diseases 'Lazzaro Spallanzani' IRCCS, Roma, Italy
Background: Innate Vgamma9Vdelta2 (Vg9Vd2) T lymphocytes are broadly reactive against various intracellular pathogens, displaying lytic responses to HIVinfected cells. Moreover, activated Vg9Vd2 T cells can suppress HIV replication
by soluble factors. In chronically HIV infected persons, dramatic reductions of
Vg9Vd2 cells number and function are found, which are partially restored by
Highly Active Anti-Retroviral Therapy (HAART).
Methods: In 7 HIV-infected patients with ongoing opportunistic infections, the effector/memory phenotype of Vg9Vd2 T cells was studied; in comparison, healthy
blood donors and cord blood from healthy newborns were studied. In 12 HIVinfected persons undergoing Structured Treatment Interruption (STI), the influence of acute plasma HIV-RNA increase on IFNgamma production (by ELISA)
and cell proliferation (by thymidine incorporation) after phosphoantigen stimulation of Vg9Vd2 T cells were studied.
Results: We observed that two subsets of Vg9Vd2 T cells could be identified
on the basis of CD27 expression in immunocompetent adults, showing that functionally differentiated gamma/delta T cells have lost CD27 expression. Differently,
the CD27- CD45RA- Vg9Vd2 T cell subset of effector cells was absent in cordblood cells from healthy newborns, and was lacking in the peripheral blood from
HIV-infected patients with ongoing opportunistic infections. In STI patients, a significant loss in Vg9Vd2 T cells number was found, and appeared restored only
one month after HAART resumption. When the effector function of Vg9Vd2 T
cells was studied, a fast and deep reduction in IFNgamma production capability
was observed during the overall STI period, followed by a restoration after HAART
resumption.

Conclusions: Altogether, these observations confirm a loss of Vg9Vd2 T cells effector activity in immunocompromised hosts occurring rapidly after viral rebound
in HIV-infected patients undergoing STI.
Presenting author: Federico Martini, National Institute for Infectious Diseases,
L.Spallanzani IRCCS, Via Portuense, 292, 00149 Roma, Italy, Tel.: [phone]
907, Fax: [phone], E-mail: [email protected]

ThPeA7134I Native HIV-1 Tat targets monocyte-derived dendritic
cells (MDDC) and enhances their maturation,
function, and antigen-specific T cell responses
E. Fanales-Belasio1, S. Moretti', F. Nappil, G. Barillari2, F. Micheletti3,
A. Cafaro1, B. Ensoli1. 1Laboratory of Virology, Istituto Superiore di SanitY,
Rome; 2Dept of Experimental Medicine, University of Tor Vergata, Rome; 3Dept.
of Biochemistry and Molecular Biology, University of Ferrara, Ferrara, Italy
Background: HIV-1 Tat is produced early after infection, is essential for virus
replication, and is released extracellularly in a biologically active form. Vaccination of cynomolgus monkeys with biologically active HIV-1 Tat protein or tat DNA,
but not with inactivated Tat or Tat peptides, induces specific Th-1 responses, including CTLs. We asked whether the native Tat protein may act differently on
antigen (Ag) presenting cells as compared with inactivated Tat or peptide Ag.
Methods: The uptake of both native or oxidized/inactivated Tat protein was evaluated by FACS after intracellular staining, in MDDC, B lymphoblastoid cell lines
(BLCL) and T cell blasts (TCB). MHC and co-stimulatory molecules expression
and cytokines and b-chemokines production were evaluated by FACS and ELISA,
respectively. Ag presenting function was determined by allogeneic cultures or with
tetanus toxoid-specific autologous lymphocytes.
Results: Biologically active Tat is very efficiently taken up by MDDC, but not by
TCB and BLCL, in a time and dose-dependent fashion. Although maturation reduces their pino/phagocytic activity, mature MDDC take up Tat much more efficiently than immature cells. Tat uptake is abolished or greatly reduced by oxidation/inactivation of the protein or at 4~C, suggesting that MDDC take up native Tat
by a receptor-mediated endocytosis. After uptake, active Tat protein induces upregulation of MHC and co-stimulatory molecules and production of IL-12, TNF-ot,
and P-chemokines, which drive Th-1 type response. In contrast, these effects are
lost by oxidation/inactivation of Tat. Finally, native Tat enhances Ag presentation
by MDDC, increasing Ag-specific T cell responses.
Conclusions: Native Tat selectively targets MDDC, is taken up by these cells
via specialized pathways, and promotes their maturation and Ag-presenting functions, driving Th-1 type immune response. The inherent immunogenicity and adjuvanticity make Tat an optimal candidate for an HIV vaccine.
Presenting author: Aurelio Cafaro, Laboratory of Virology, Istituto Superiore di
Sanita', Viale Regina Elena, 299, 00161 Rome, Italy, Tel.: [phone], Fax:
[phone], E-mail: [email protected]
ThPeA7135 INK cell phenotype and function in HIV-infected
patients during Structured Treatment Interruptions
(STI)
C. Nisii, C. Montesano, F Martini, C. Gioia, R. Caseti, G. D'Offizi, F Poccia,
G. Antonucci, G. Ippolito, A. Oliva. NationalInstitute for Infectious Diseases
'L.Spallanzani, Rome, Italy
Background: Recent reports described the dynamics of HIV-specific immune
response during Structured Treatment Interruptions (STI). We analyzed the influence of STI on innate NK immunity.
Methods: NK cell phenotype and function (determined as IFNy production)
were evaluated by flow cytometry, analyzing PBMCs from 5 HIV- subjects and
9 HIV+ patients undergoing STI. The assays were performed at the suspension
of HAART (tO), 1 month (tl) and 2 months (t2) after suspension, and 15 days (t3)
and 1 month (t4) after HAART resumption.
Results: The percentage of both NK cells (CD3-CD56+) and perforin-positive
cells of HIV+ patients did not vary significantly neither at the time points studied, nor when compared to controls. Surface marker CD94 (lectin-like dimer) was
higher in NK cells from HIV+ (75% CD94+) than from HIV- (55% CD94+). 80% of
controls vs. 56%(t0), 29% (tl), 67% (t2), 67%(t3) and 56% (t4) of HIV+ showed
a significant IFNy production by NK cells. The drop in IFNy production at tl was
correlated with an increased expression of CD158 (killer cell Ig-like receptor) and
with a reduced frequency of CD3-CD56+IFNy+ cells. Although fewer HIV+ than
HIV- individuals were IFNy producers, the percentage of IFNy+ NK cells was consistently higher in HIV+ patients at all time points studied (t0=6.7+-3.9%, t2=7.5+5%, t3=7.8+-5.6%, t4=6.6+-5.1) but ti (2.5+-2.4) in comparison to normal donors
(3.9+-1.3). Two of the IFNy producer patients had a delayed viral rebound, while
all the others had a fast increase of viral load, within 2 months after suspension.
Conclusions: NK cell subset composition is different in HIV-infected people in
comparison to controls. HAART suspension deeply affects NK cell function, inducing a reduction of IFNy production, restored to basal values after resumption
of therapy. Control of viremia during STI is, in some cases, correlated to an efficient NK activity.
Presenting author: Carla Nisii, National Institute for Infectious Diseases, Lazzaro Spallanzani IRCCS, Via Portuense, 292, 00149 Roma, Italy, Tel.: +39 06
55170954, Fax: [phone], E-mail: [email protected]

ThPeA7136 ICervical intraepithelial T lymphocyte activation and
chemokine receptor expression HIV-1 infected
women
M. Prakash1, S. Patterson1, F Gotch1, M.S. Kapembwa2. 1lmperial College,
London, Dept Immunology, Chelsea & Westminster Hospital, London, United
Kingdom; 2Dept HIV/GUM Medicine Imperial College, London, United Kingdom
Background: Heterosexual transmission is the predominant route of HIV-1 infec