[Association of PD-1 expression on CD4+ CD25 nt/hi CD127 lo regulatory T cells with disease progression in HIV-1 infected patients].

Aim: To investigate whether Programmed death-1 (PD-1) expression on peripheral CD4(+)CD25(nt/hi)CD127(lo) regulatory T cells (Treg) was associated with disease progression in HIV-1-infected patients.

Methods: Peripheral blood from 108 HIV-1-infected patients in distinct disease progression statuses and 27 healthy individuals were collected in the present investigation. PBMCs were isolated by centrifugation on Ficoll-Hypaque, followed by staining with anti-CD4-PerCP, anti-CD25-FITC, anti-CD127-PE and anti-PD-1-APC. PD-1 expression on Treg was analyzed by four-color staining flow cytometry. CD4(+) T cell absolute counts were determined using Multitest CD3/CD4/CD8/CD45 kit and plasma viral loads were detected on NucliSens EasyQ. All data were analyzed using SPSS14.0 software.

Results: In peripheral blood of healthy individuals, Treg expressed PD-1 at very low levels (1.72%+/-0.65%). In contrast, Treg from HIV-1-infected patients showed a significantly increased PD-1 expression (5.33%+/-2.24%, P<0.01). Moreover, AIDS patients exhibited statistically higher PD-1 expression on Treg (7.87%+/-2.23%) than newly HIV-1 infected patients (3.22%+/-1.01%, P<0.05) and patients in progression to AIDS(5.21%+/-1.72%, P<0.05). PD-1 up-regulation on Treg was closely correlated with reduced CD4(+) T cell absolute counts but elevated plasma viral load.

Conclusion: Overall, we found that PD-1 expression on peripheral Treg was up-regulated and correlated with disease progression in HIV-1-infected patients for the first time. These findings not only extend our understanding of how Treg functions in HIV-1-infected patients but also support the notion that blocking PD-1/PD-L1 interactions may represent a potential therapeutic strategy for HIV-1-infected patients.