Human immunodeficiency virus type 1 (HIV-1) antigen secretion by latently infected resting CD4+ T lymphocytes from HIV-1-infected individuals

Abstract

In resting CD4(+) T lymphocytes harboring human immunodeficiency virus type 1 (HIV-1), replication-competent virus persists in patients responding to highly active antiretroviral therapy (HAART). This small latent reservoir represents between 10(3) and 10(7) cells per patient. However, the efficiency of HIV-1 DNA-positive resting CD4(+) T cells in converting to HIV-1-antigen-secreting cells (HIV-1-Ag-SCs) after in vitro CD4(+)-T-cell polyclonal stimulation has not been satisfactorily evaluated. By using an HIV-1-antigen enzyme-linked immunospot assay, 8 HIV-1-Ag-SCs per 10(6) CD4(+) resting T cells were quantified in 25 patients with a plasma viral load of <20 copies/ml, whereas 379 were enumerated in 10 viremic patients. In parallel, 369 and 1,238 copies of HIV-1 DNA per 10(6) CD4(+) T cells were enumerated in the two groups of patients, respectively. Only a minority of latently HIV-1 DNA-infected CD4(+) T cells could be stimulated in vitro to become HIV-1-Ag-SCs, particularly in aviremic patients. The difference between the number of HIV-1 immunospots in viremic versus aviremic patients could be explained by HIV-1 unintegrated viral DNA that gave additional HIV-1-Ag-SCs after in vitro CD4(+)-T-cell polyclonal stimulation. The ELISPOT approach to targeting the HIV-1-Ag-SCs could be a useful method for identifying latently HIV-1-infected CD4(+) T cells carrying replication-competent HIV-1 in patients responding to HAART.

FIG. 1.

Efficiency of ex vivo spontaneously activated CD4⁺-T-cell elimination. Enrichments of CD4⁺ T cells (I and II) were characterized according to membrane HLA-DR receptor expression (Ib and IIb). Aliquots of CD4⁺ T cells were incubated with a mixture of phycoerythrin-cyanin 5 (PC5)-conjugated anti-CD4 and fluorescein isiothiocyanate (FITC)-conjugated anti-HLA-DR antibodies (Beckman-Coulter). (I) Purified CD4⁺ T cells. (II) Ex vivo-activated CD4⁺ T cells were eliminated using magnetic beads coupled with anti-HLA-DR monoclonal Ab (Dynal). The horizontal line separating the HLA-DR negative and positive subpopulations was defined using an isotypic control (Ia and IIa).