Phenotypes and HIV-1-specific T cell responses of KIR3DL1 positive CD8 cells in patients with early HIV-1 infection
Objective 
To investigate the phenotypes and the HIV-1-specific T cell responses of KIR3DL1 positive CD8 cells in patients with early HIV-1 infection. 
 
 
Methods 
Fifty-six HIV-1 antibody negative individuals and thirty-two patients with early HIV-1 infection were enrolled in the study. Fluorescence-activated cell sorting (FACS) was performed to detect the phenotypes of KIR3DL1 receptor expressed on the surface of CD8 cells. The levels of IFN-γ were measured by intracellular cytokine staining assay after the PBMCs were stimulated with an HIV-1 Gag peptide pool. 
 
 
Results 
The percentages of KIR3DL1+ CD8 T cells in HIV-1 negative individuals and patients with early HIV-1 infection were 1.45% (0.12%-8.4%) and 0.82% (0.14%-6.14%), respectively, and there was no significant difference between them. The percentages of KIR3DL1+ CD8 Temra cells in HIV-1 negative individuals and patients with early HIV-1 infection were (4.55±3.84)% and (6.71±8.50)%, respectively, which were significantly higher than the percentages of KIR3DL1+ CD8 Tem cells, which were (0.50±0.59)% and (1.18±1.39)%, respectively (all P<0.01). Moreover, the percentages of KIR3DL1+ CD8 Tem cells in patients with early HIV-1 infection were higher than those in HIV-1 negative individuals (P=0.001 2). The percentage of KIR3DL1+ CD8 Temra cells was positively correlated with the HIV-1 viral load in patients with early HIV-1 infection (rs=0.576, P=0.000 9). The percentages of KIR3DL1+ CD8 Temra cells in HIV-1 patients, whose viral loads were larger than 4.0log, were much higher than those in HIV-1 patients with viral loads less than 4.0 log (P=0.002). Additionally, the levels of IFN-γ secreted by KIR3DL1 positive CD8 cells were much lesser than those secreted by KIR3DL1 negative CD8 cells (P<0.000 1). 
 
 
Conclusion 
The receptor of KIR3DL1 was mainly expressed on CD8 Temra cells in both HIV-1 negative subjects and patients with early HIV-1 infection. High HIV-1 viremia was associated with the high percentage of KIR3DL1+ CD8 Temra cells. The KIR3DL1 positive CD8 cells induced lower HIV-1-specific T cell responses. 
 
 
Key words: 
Early HIV-1 infection; KIR3DL1 receptor; CD8 cells