Regulatory T cells and viral infections.
Viral infections often lead to generalized immunosuppression characterized by the downregulation of virus-specific CD4+ and CD8+ T cell responses and/or non-specific inflammation. One of the mechanisms for the virus-induced immunosuppression is the induction of CD4+ CD25+ regulatory T (Treg) cells that act to suppress effector T cell functions during infection. Depending on the situation, the CD4+ CD25+ Treg cell-mediated suppression can be either beneficial or detrimental to the host. On one hand, they play a critical role in maintaining host homeostasis by controlling exaggerated and destructive inflammations paralleling strong antiviral immune responses and thus contribute to host protection. On the other hand, suppression of virus-specific T cell responses by the Treg cells depresses host antiviral immune responses and thus facilitates viral persistence and disease progression. Despite numerous reports on induction of CD4+ CD25+ Treg cells in viral infections, it is still not fully clear how they are induced and how they act to suppress effector T cell functions in viral infections. This review discusses recent progress in our understanding of the role of virus-induced CD4+ CD25+ Treg cells and the mechanisms by which they are induced and exert their function during infection.
Zhou
Yaling
Y
Department of Clinical Investigation, Walter Reed Army Medical Center, 6900 Georgia Ave. NW, Washington, DC 20307, USA. yaling.zhou@na.amedd.army.mil
D000818:Animals; D001327:Autoimmune Diseases / Q000097:blood; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D003713:Dendritic Cells / Q000378:metabolism; D015967:Gene Expression Regulation, Viral; D006801:Humans; D007107:Immune System; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D007249:Inflammation; D053645:Interleukin-2 Receptor alpha Subunit / Q000096:biosynthesis; D008954:Models, Biological; D050378:T-Lymphocytes, Regulatory / Q000378:metabolism* / Q000821:virology*; D014777:Virus Diseases / Q000097:blood* / Q000378:metabolism
D016207:Cytokines; D007166:Immunosuppressive Agents; D053645:Interleukin-2 Receptor alpha Subunit