HIV-specific CD8(+) T cells produce antiviral cytokines but are impaired in cytolytic function.
The use of peptide-human histocompatibility leukocyte antigen (HLA) class I tetrameric complexes to identify antigen-specific CD8(+) T cells has provided a major development in our understanding of their role in controlling viral infections. However, questions remain about the exact function of these cells, particularly in HIV infection. Virus-specific cytotoxic T lymphocytes exert much of their activity by secreting soluble factors such as cytokines and chemokines. We describe here a method that combines the use of tetramers and intracellular staining to examine the functional heterogeneity of antigen-specific CD8(+) T cells ex vivo. After stimulation by specific peptide antigen, secretion of interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, macrophage inflammatory protein (MIP)-1beta, and perforin is analyzed by FACS((R)) within the tetramer-positive population in peripheral blood. Using this method, we have assessed the functional phenotype of HIV-specific CD8(+) T cells compared with cytomegalovirus (CMV)-specific CD8(+) T cells in HIV chronic infection. We show that the majority of circulating CD8(+) T cells specific for CMV and HIV antigens are functionally active with regards to the secretion of antiviral cytokines in response to antigen, although a subset of tetramer-staining cells was identified that secretes IFN-gamma and MIP-1beta but not TNF-alpha. However, a striking finding is that HIV-specific CD8(+) T cells express significantly lower levels of perforin than CMV-specific CD8(+) T cells. This lack of perforin is linked with persistent CD27 expression on HIV-specific cells, suggesting impaired maturation, and specific lysis ex vivo is lower for HIV-specific compared with CMV-specific cells from the same donor. Thus, HIV-specific CD8(+) T cells are impaired in cytolytic activity.
Appay
V
V
Medical Research Council Human Immunology Unit, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford OX3 9DS, United Kingdom.
Nixon
D F
DF
Donahoe
S M
SM
Gillespie
G M
GM
Dong
T
T
King
A
A
Ogg
G S
GS
Spiegel
H M
HM
Conlon
C
C
Spina
C A
CA
Havlir
D V
DV
Richman
D D
DD
Waters
A
A
Easterbrook
P
P
McMichael
A J
AJ
Rowland-Jones
S L
SL
D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000821:virology*; D054407:Chemokine CCL4; D002999:Clone Cells; D016207:Cytokines / Q000096:biosynthesis*; D003587:Cytomegalovirus / Q000276:immunology; D005434:Flow Cytometry; D006678:HIV / Q000276:immunology*; D015658:HIV Infections / Q000276:immunology*; D018023:HIV Seronegativity / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D019402:Macrophage Inflammatory Proteins / Q000096:biosynthesis; D012016:Reference Values; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000821:virology*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
D054407:Chemokine CCL4; D016207:Cytokines; D015395:Histocompatibility Antigens Class I; D019402:Macrophage Inflammatory Proteins; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma