Energizing Lymphocytes Exhausted by Fighting Viruses

In a new report, researchers suggest that natural T-cell responses against HIV can be enhanced. Previously, investigators found that, in mice, a lymphocyte receptor called programmed death 1 (PD-1) and a molecule that binds to this receptor (PD-L1) affect the antiviral activity of CD4⁺ and CD8⁺ lymphocytes.

An international team studied HIV-positive people in South Africa who had never been treated with antiretroviral drugs. They found that the PD-1 receptor is upregulated in CD4⁺ and CD8⁺ T cells that are primed to attack HIV. Moreover, the higher the concentration of PD-1 in CD4⁺ or CD8⁺ cells, the higher the viral load and the lower the CD4⁺ cell count. When antibody against the PD-L1 molecule was added during in vitro experiments to bloc…