Association between Peripheral γδ T-cell Profile and Disease Progression in Individuals Infected with HIV-1 or HIV-2 in West Africa

Abstract

Background:

Human gammadelta (γδ) T cells play an important role in protective immunity in HIV-1 and SIV infection; their role in HIV-2 infection is unknown.

Objective:

To determine the role of γδ T cells in control of plasma viral load and CD4 ⁺ T-cell count in HIV-1 and HIV-2 infections in West Africa.

Methods:

Thirty HIV-1 and 25 HIV-2 treatment-naïve chronically infected individuals, as well as 20 HIV-seronegative individuals from Senegal were studied using multi-parametric flow cytometry to investigate the frequencies and phenotypes of peripheral γδ T-cells. γδ T-cells parameters and correlates of HIV disease progression were assessed.

Results:

We observed an expansion of Vδ1 ⁺ T-cell populations in both HIV-1 and HIV-2 infection. However, unlike HIV-1 infection, no significant contraction of the frequency of total Vδ2 ⁺ T cells was observed in HIV-2 infection. Significantly lower frequencies of CD4 ⁺Vδ2 ⁺ T cells were observed in HIV-2 infected individuals. Furthermore, frequencies of CD28 ⁻CD45RO ⁺ and CD27 ⁻CD28 ⁻CD45RO ⁻ Vδ2 ⁺ T-cell were low in HIV-1 infected individuals. Vδ2 ⁺ T-cell activation levels were elevated in both HIV-1 and HIV-2 infected individuals. The frequency of HLA-DR ⁻CD38 ⁺ activated Vδ1 ⁺ and Vδ2 ⁺ T-cells was associated with a decline in CD4 ⁺ T-cell counts and increased viral load in both HIV-1 and HIV-2 infection.

Conclusion:

While maintaining the normal frequency of total Vδ2 ⁺ T cells, HIV-2 infection reduces the frequency of CD4 ⁺Vδ2 ⁺ T cells and alters the frequencies of subsets of Vδ1 ⁺ T cells. Both HIV-1 and HIV-2 infection induce γδ T cell activation, and this activation is associated with the disease progression.