HIV-1-Specific Memory CD4+ T Cells Are Phenotypically Less Mature Than Cytomegalovirus-Specific Memory CD4+ T Cells

Abstract

HIV-1-specific CD4+ T cells are qualitatively dysfunctional in the majority of HIV-1-infected individuals and are thus unable to effectively control viral replication. The current study extensively details the maturational phenotype of memory CD4+ T cells directed against HIV-1 and CMV. We find that HIV-1-specific CD4+ T cells are skewed to an early central memory phenotype, whereas CMV-specific CD4+ T cells generally display a late effector memory phenotype. These differences hold true for both IFN-γ- and IL-2-producing virus-specific CD4+ T cells, are present during all disease stages, and persist even after highly active antiretroviral therapy (HAART). In addition, after HAART, HIV-1-specific CD4+ T cells are enriched for CD27+CD28−-expressing cells, a rare phenotype, reflecting an early intermediate stage of differentiation. We found no correlation between differentiation phenotype of HIV-1-specific CD4+ T cells and HIV-1 plasma viral load or HIV-1 disease progression. Surprisingly, HIV-1 viral load affected the maturational phenotype of CMV-specific CD4+ T cells toward an earlier, less-differentiated state. In summary, our data indicate that the maturational state of HIV-1-specific CD4+ T cells cannot be a sole explanation for loss of containment of HIV-1. However, HIV-1 replication can affect the phenotype of CD4+ T cells of other specificities, which might adversely affect their ability to control those pathogens. The role for HIV-1-specific CD4+ T cells expressing CD27+CD28− after HAART remains to be determined.