Increased PD-L1 expression has been reported in HIV-1-infected individuals, but the mechanisms leading to PD-L1 upregulation remain to be elucidated. Here we demonstrate that HIV-1-derived Toll-like receptor (TLR)7/8 ligands can induce MyD88-dependent upregulation of PD-L1 on plasmacytoid dendritic cells, myeloidic dendritic cells and monocytes. These data suggest a mechanism through which HIV-1-derived TLR ligands might contribute to the functional impairment of virus-specific PD-1-positive T cells by inducing the upregulation of PD-L1 on antigen-presenting cells.
aPartners AIDS Research Center, Massachusetts General Hospital, Division of AIDS, Harvard Medical School, Boston, Massachusetts, USA
bDepartment of Anesthesia and Critical Care, Massachusetts General Hospital, Boston, Massachusetts, USA.
Received 22 August, 2007
Revised 21 November, 2007
Accepted 26 November, 2007