Taking off the brakes: T cell immunity in the liver.
In lymphatic tissue, professional antigen-presenting cells (APCs) such as dendritic cells (DCs), mature after sensing microbe-associated molecular patterns (MAMPs) by pattern recognition receptors (PRRs), and subsequently activate T cell immunity. Non-pathogenic MAMPs, derived for example from commensal bacteria, are delivered to the liver from the gastrointestinal tract via the portal vein. However, in contrast to splenic DCs, PRRs-expressing liver APCs induce T cell tolerance rather than immunity. This is explained partly by the distinct effects of PRRs on the maturation of liver APCs: these cells activate T cell immunity only when PRRs stimulation is accompanied by microbial infection through mechanisms that are not employed by DCs in lymphatic tissue. Understanding the molecular basis of T cell tolerance and immunity in the liver may help develop novel immune therapy for persistent viral infection or liver cancer.
Kern
M
M
Institutes of Molecular Medicine and Experimental Immunology, University of Bonn, Germany.
Popov
A
A
Kurts
C
C
Schultze
J L
JL
Knolle
P A
PA
D000818:Animals; D003713:Dendritic Cells / Q000276:immunology; D006649:Histocompatibility Antigens / Q000276:immunology; D006801:Humans; D007108:Immune Tolerance; D008099:Liver / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*
D006649:Histocompatibility Antigens