CD8+ T cell tolerance following antigen recognition on hepatocytes

Area of Science:

• Immunology
• Hepatology
• Virology

Background:

• Hepatocytes are the primary target cells for Hepatitis C Virus (HCV).
• Traditionally considered to have low Class I MHC expression, hepatocytes are now recognized for their role in intrahepatic immune responses.
• Their antigen-presenting capabilities are crucial for T cell activation within the liver.

Purpose of the Study:

• To review evidence supporting hepatocytes as in vivo antigen-presenting cells.
• To explore the consequences of T cell activation by hepatocytes.
• To propose a mechanism by which early T cell activation by hepatocytes contributes to HCV persistence.

Main Methods:

• Review of existing literature and data on hepatocyte immune function.
• Analysis of electron micrographs showing T cell-hepatocyte interactions.
• Exploration of T cell fate following activation by hepatocytes.

Main Results:

• Hepatocytes express high levels of antigen-presentation molecules, polarized towards sinusoidal lumen for efficient T cell activation.
• In vivo T cell-hepatocyte interactions occur via fenestrations in sinusoidal endothelial cells.
• Early activation of naive CD8+ T cells by hepatocytes is proposed as a critical event in HCV infection.

Conclusions:

• Hepatocytes function as potent antigen-presenting cells in vivo.
• Early T cell activation by hepatocytes during HCV infection may lead to viral persistence.
• This process contributes to viral persistence through the removal of virus-specific T cells from the T cell repertoire.