HLA-E-restricted CD8 + T Lymphocytes Efficiently Control Mycobacterium tuberculosis and HIV-1 Coinfection

We investigated the contribution of human leukocyte antigen A2 (HLA-A2) and HLA-E-restricted CD8 T cells in patients with and human immunodeficiency virus 1 (HIV-1) coinfection. HIV-1 downregulates HLA-A, -B, and -C molecules in infected cells, thus influencing recognition by HLA class I-restricted CD8 T cells but not by HLA-E-restricted CD8 T cells, owing to the inability of the virus to downmodulate their expression. Therefore, antigen-specific HLA-E-restricted CD8 T cells could play a protective role in and HIV-1 coinfection. HLA-E- and HLA-A2-restricted -specific CD8 T cells were tested for cytotoxic and microbicidal activities, and their frequencies and phenotypes were evaluated in patients with active tuberculosis and concomitant HIV-1 infection. HIV-1 and coinfection caused downmodulation of HLA-A2 expression in human monocyte-derived macrophages associated with resistance to lysis by HLA-A2-restricted CD8 T cells and failure to restrict the growth of intracellular . Conversely, HLA-E surface expression and HLA-E-restricted cytolytic and microbicidal CD8 responses were not affected. HLA-E-restricted and -specific CD8 T cells were expanded in the circulation of patients with /HIV-1 coinfection, as measured by tetramer staining, but displayed a terminally differentiated and exhausted phenotype that was rescued by anti-PD-1 (programmed cell death protein 1) monoclonal antibody. Together, these results indicate that HLA-E-restricted and -specific CD8 T cells in patients with /HIV-1 coinfection have an exhausted phenotype and fail to expand in response to antigen stimulation, which can be restored by blocking the PD-1 pathway using the specific monoclonal antibody nivolumab.