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Journal of Virology, September 2001, p. 8306-8316, Vol. 75, No. 17
Partners AIDS Research Center and Infectious
Disease Division, Massachusetts General Hospital and Harvard
Medical School, Boston, Massachusetts 02129
Received 14 December 2000/Accepted 1 June 2001
Human immunodeficiency virus (HIV)-specific cytotoxic T lymphocytes
(CTL) mediate immunologic selection pressure by both cytolytic and
noncytolytic mechanisms. Non cytolytic mechanisms include the release
of
0022-538X/01/$04.00+0 DOI: 10.1128/JVI.75.17.8306-8316.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Noncytolytic Inhibition of X4 Virus by Bulk
CD8+ Cells from Human Immunodeficiency Virus Type 1 (HIV-1)-Infected Persons and HIV-1-Specific Cytotoxic T Lymphocytes
Is Not Mediated by
-Chemokines
-chemokines blocking entry of R5 HIV-1 strains. In addition,
CD8+ cells inhibit X4 virus isolates via release of as yet
poorly characterized soluble factors. To further characterize these
factors, we performed detailed analysis of CTL as well as bulk
CD8+ T lymphocytes from six HIV-1-infected individuals and
from six HIV-1-seronegative individuals. Kinetic studies revealed that secreted suppressive activities of HIV-1-specific CTL and bulk CD8+ T lymphocytes from all HIV-1-infected persons are
significantly higher than that of supernatants from seronegative
controls. The suppressive activity could be blocked by monensin and
brefeldin A, was heat labile, and appeared in a pattern different from
that of secretion of chemokines (MDC, I-309, MIP-1
, MIP-1
, and
RANTES), cytokines (gamma interferon, tumor necrosis factor alpha, and granulocyte-macrophage colony-stimulating factor), and interleukins (interleukin-13 and interleukin-16). This suppression activity was
characterized by molecular size exclusion centrifugation and involves a
suppressive activity of >50 kDa which could be bound to heparin and a
nonbinding inhibitory activity of <50 kDa. Our data provide a
functional link between CD8+ cells and CTL in the
noncytolytic inhibition of HIV-1 and suggest that suppression of X4
virus is mediated through proteins. The sizes of the proteins, their
affinity for heparin, and the pattern of release indicate that these
molecules are not chemokines.
*
Corresponding author. Mailing address: Partners AIDS
Research Center, 149 13th St., Charlestown, MA 02129. Phone: (617)
724-8332. Fax: (617) 726-4691. E-mail:
bwalker{at}helix.mgh.harvard.edu.
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