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The function of invariant chain in class II-restricted antigen presentation
Seminars in Immunology
|December 1, 1995
Summary
The invariant chain (Ii) is crucial for assembling and presenting antigen-class II peptide complexes. This protein facilitates multiple steps in antigen presentation, acting as a chaperone and T-cell ligand.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- The invariant chain (Ii) plays a critical role in the function of Major Histocompatibility Complex (MHC) class II molecules.
- Understanding Ii's function is key to deciphering antigen presentation pathways.
Purpose of the Study:
- To elucidate the multifaceted roles of the invariant chain (Ii) in the assembly and presentation of antigen-class II peptide complexes.
- To review evidence from reconstitution studies and knockout mice regarding Ii function.
Main Methods:
- Reconstitution of cell lines with MHC class II molecules and invariant chain variants.
- Generation and analysis of genetically modified mice lacking functional invariant chain expression.
Main Results:
- Invariant chain (Ii) facilitates MHC class II assembly in the endoplasmic reticulum (ER).
- Ii chaperones and retains properly folded MHC class II complexes in endosomal compartments.
- Ii functions as a ligand for T-cell receptors, influencing immune responses.
Conclusions:
- Invariant chain (Ii) performs multiple roles throughout the antigen presentation pathway.
- Ii's function is context-dependent, influenced by antigen type, administration route, and experimental system.
- Ii may increase MHC class II availability, modulate endosomal trafficking, facilitate peptide exchange, and alter the antigen processing environment.