Loss of Fas (CD95) expression by dendritic cells protects from a chronic viral infection

Chronic viral infections incapacitate adaptive immune responses by 'exhausting' virus-specific T cells, inducing their deletion and reducing productive T cell memory. Viral infection rapidly induces death receptor Fas (CD95) expression by dendritic cells (DCs) making them susceptible to elimination by the immune response. Lymphocytic Choriomeningitis Virus (LCMV) Clone 13, which normally establishes a chronic infection, is rapidly cleared in C57Black/J mice with conditional deletion of Fas in DCs. The immune response to LCMV is characterized by an extended survival of virus-specific effector T cells. Moreover, transfer of Fas-negative DCs from non-infected mice to already-infected animals results in either complete clearance of the virus or a significant reduction of viral titers. Thus, DC-specific Fas expression plays a role in regulation of anti-viral responses and suggests a strategy for stimulation of T cells in chronically infected animals and humans in order to achieve the clearance of persistent viruses. We compared gene expression between splenic DCs from B6.FasKI and B6.CD11c-Cre.FasKI mice. DCs were isolated on day 5 after LCMV infection with 3 mice in each group, for a total of 6 samples. Spleens were collagenase-DNAse digested and sorted by flow to isolate DCs.