HIV-1-specific T cell precursors with high proliferative capacity correlate with low viremia and high CD4 counts in untreated individuals.
Evidences have recently suggested that the preservation of vaccine-induced memory rather than effector T cells is essential for better outcome and survival following pathogenic SIV challenge in macaques. However, an equivalent demonstration in humans is missing, and the immune correlates of HIV-1 control have been only partially characterized. We focused on the quantification of Ag-specific T cell precursors with high proliferative capacity (PHPC) using a peptide-based cultured IFN-gamma ELISPOT assay (PHPC assay), which has been shown to identify expandable memory T cells. To determine which responses correlate with viral suppression and positive immunologic outcome, PBMC from 32 chronically untreated HIV-1-infected individuals were evaluated in response to peptide pools, representing the complete HIV-1 Gag, Nef, and Rev proteins, by PHPC and IFN-gamma ELISPOT assay, which instead identifies effector T cells with low proliferative capacity. High magnitude of Gag-specific PHPC, but not ELISPOT, responses significantly correlated with low plasma viremia, due to responses directed toward p17 and p15 subunits. Only Gag p17-specific PHPC response significantly correlated with high CD4 counts. Analysis of 20 additional PBMC samples from an independent cohort of chronically untreated HIV-1-infected individuals confirmed the correlation between Gag p17-specific PHPC response and either plasma viremia (inverse correlation) or CD4 counts (direct correlation). Our results indicate that the PHPC assay is quantitatively and qualitatively different from the ELISPOT assay, supporting that different T cell populations are being evaluated. The PHPC assay might be an attractive option for individual patient management and for the design and testing of therapeutic and prophylactic vaccines.
Calarota
Sandra A
SA
Research Institute for Genetic and Human Therapy, Fondazione Istituto de Ricovero e Cura a Carattere Scientifico, Policlinoco San Matteo, Piazzale Golgi 2, Pavia, Italy.
Foli
Andrea
A
Maserati
Renato
R
Baldanti
Fausto
F
Paolucci
Stefania
S
Young
Mary A
MA
Tsoukas
Christos M
CM
Lisziewicz
Julianna
J
Lori
Franco
F
D016915:AIDS Vaccines / Q000276:immunology / Q000378:metabolism; D000818:Animals; D018791:CD4 Lymphocyte Count; D049109:Cell Proliferation; D002908:Chronic Disease; D015331:Cohort Studies; D005260:Female; D016655:HIV Core Protein p24 / Q000276:immunology / Q000378:metabolism; D015658:HIV Infections / Q000097:blood / Q000276:immunology* / Q000517:prevention & control; D015497:HIV-1 / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000276:immunology / Q000378:metabolism; D008251:Macaca; D008297:Male; D054504:Precursor Cells, T-Lymphoid / Q000276:immunology* / Q000378:metabolism / Q000821:virology; D016097:Simian Acquired Immunodeficiency Syndrome / Q000097:blood / Q000276:immunology; D015302:Simian Immunodeficiency Virus / Q000276:immunology / Q000378:metabolism; D014766:Viremia / Q000276:immunology* / Q000517:prevention & control
D016915:AIDS Vaccines; D016655:HIV Core Protein p24; D007371:Interferon-gamma