CD8+ T-cell-mediated suppression of HIV-1 long terminal repeat-driven gene expression is not modulated by the CC chemokines RANTES, macrophage inflammatory protein (MIP)-1 alpha and MIP-1 beta.
OBJECTIVE
To assess the role of RANTES, macrophage inflammatory protein (MIP)-1 alpha and MIP-1 beta in modulation of HIV-1 long terminal repeat (LTR)-mediated gene expression and determine whether these chemokines share identity with CD8+ T-lymphocyte-derived HIV-1 LTR-suppressive factors.


METHODS
HIV-1 LTR-directed reporter gene expression is a model for transcription that is susceptible to inhibition by factors produced by CD8+ lymphocytes of HIV-1-infected individuals. The effect of recombinant chemokines on LTR-directed gene expression was examined. The ability of chemokines found to be present in CD8 supernatants to suppress HIV-1 LTR-mediated gene expression was determined by antibody inhibition assays.


METHODS
The concentrations of RANTES, MIP-1 alpha and MIP-1 beta in a panel of CD8+ T-lymphocyte-derived supernatants were determined by enzyme-linked immunosorbent assay. Recombinant chemokines were added to freshly transfected (pLTR-CAT and pSV40-tat) human Jurkat T cells. Excessive polyclonal neutralizing antibodies to these chemokines were added to transfected Jurkat T cells cultured in the presence of strongly inhibitory CD8+ T-cell-derived supernatants with known chemokine concentrations.


RESULTS
The concentrations of RANTES, MIP-1 alpha and MIP-1 beta in a panel of CD8+ lymphocyte-derived supernatants were found to correlate with their relative ability to suppress the LTR-mediated gene expression (r = 0.679, 0.764 and 0.48, respectively). The addition of recombinant CC chemokines had no effect over a broad range of doses on HIV-1 LTR-mediated gene expression. The CD8-suppressive effect on HIV-1 LTR-driven gene expression was not abrogated by a combination of antibodies of RANTES, MIP-1 alpha and MIP-1 beta.


CONCLUSIONS
RANTES, MIP-1 alpha and MIP-1 beta do not alter HIV-1 LTR-directed gene expression at doses up to 100 ng/ml. Although present in varying concentrations in supernatants derived from CD8+ lymphocytes from HIV-positive individuals, these chemokines are not responsible for the powerful CD8-derived suppressive effect on HIV-1 LTR-mediated gene expression observed in our system.
Leith
J G
JG
Department of Pathology, McMaster University Health Sciences Centre, Hamilton, Ontario, Canada.
Copeland
K F
KF
McKay
P J
PJ
Richards
C D
CD
Rosenthal
K L
KL
D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000821:virology*; D002478:Cells, Cultured; D054407:Chemokine CCL4; D018946:Chemokine CCL5 / Q000494:pharmacology*; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D015967:Gene Expression Regulation, Viral / Q000187:drug effects*; D015658:HIV Infections / Q000276:immunology / Q000821:virology*; D016325:HIV Long Terminal Repeat / Q000235:genetics*; D015497:HIV-1 / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D019402:Macrophage Inflammatory Proteins / Q000494:pharmacology*
D054407:Chemokine CCL4; D018946:Chemokine CCL5; D019402:Macrophage Inflammatory Proteins