Dendritic cell amplification of HIV type 1-specific CD8+ T cell responses in exposed, seronegative heterosexual women.
In the Heterosexual AIDS Transmission Study (HATS), the frequency of high-risk sexual activity and viral load in the seropositive partner were shown to correlate with HIV-1 transmission. However, these parameters could not account for the status of some exposed, seronegative (ESN) individuals who remained uninfected despite years of exposure. To test the hypothesis that antiviral immune responses are a correlate of nontransmission in this cohort, we developed two sensitive methods for assessing HIV-1-specific humoral and cell-mediated responses. To quantify T cell responses, autologous mature dendritic cells (DCs) were used as antigen-presenting cells to elicit HIV-1-specific IFN-gamma production by ELISPOT. Antibody responses to HIV-1 gp120 were assessed by combination immunoprecipitation-Western blot (IP-WB). Previous studies of this cohort, using limiting dilution analysis, did not reveal HIV-1-specific cytotoxic T lymphocyte activity. However, when autologous DCs were used to present HIV-1 antigens, T cells from three of eight ESN women (38%) responded by producing IFN-gamma. T cells from three of four seropositive partners responded to HIV-1 antigens, whereas five negative controls did not. The use of DCs as antigen-presenting cells increased sensitivity by 2- to 30-fold relative to standard ELISPOT. Using IP-WB, low levels of gp120-reactive antibodies were detected in plasma from 1 of 14 ESN women. These results support the hypothesis that HIV-1-specific T cell responses play a role in immune surveillance in this cohort of North American serodiscordant couples. This report also demonstrates the ability of dendritic cells to reveal T cell responses that might be overlooked by other methods.
Shacklett
Barbara L
BL
Gladstone Institute of Virology and Immunology, University of California-San Francisco, PO Box 419100, San Francisco, CA 94110-9100, USA. bshacklett@gladstone.ucsf.edu
Means
Robert E
RE
Larsson
Marie
M
Wilkens
David T
DT
Beadle
Thomas J
TJ
Merritt
Melissa J
MJ
Bhardwaj
Nina
N
Palumbo
Paul E
PE
Skurnick
Joan H
JH
Louria
Donald B
DB
Nixon
Douglas F
DF
D015153:Blotting, Western; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D003713:Dendritic Cells / Q000502:physiology*; D005260:Female; D018023:HIV Seronegativity / Q000276:immunology*; D006679:HIV Seropositivity / Q000276:immunology; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D012680:Sensitivity and Specificity