What is the function of the Major Histocompatibility Complex (MHC)?

From the Guidelines

The Major Histocompatibility Complex (MHC) plays a crucial role in presenting peptides to T cells, facilitating the immune system's ability to distinguish between self and non-self, as evident from the recent study published in 2020 1. The MHC molecules are responsible for presenting fragments of proteins (peptides) to T cells, which enables the immune system to recognize and respond to foreign substances.

• MHC class I presents peptides from inside the cell to CD8+ T cells,
• while MHC class II presents peptides from outside the cell to CD4+ T cells, as described in the study published in the Annals of Oncology 1. The process of antigen presentation involves the breakdown of proteins into peptides, which are then loaded onto MHC molecules and transported to the cell surface for interaction with T cell receptors.
• The binding affinity and stability of the peptide-MHC complex,
• peptide competition for MHC binding,
• the diversity of the T-cell receptor (TCR) repertoire,
• the propensity of the CD8+ TCR to recognize the peptide-HLA complex,
• and neoantigen foreignness are all factors that influence immunogenicity, as highlighted in the study 1. The MHC's ability to present a wide variety of peptides is essential for comprehensive immune surveillance against numerous pathogens, and its extreme polymorphism creates diverse binding grooves that enable targeted responses against specific threats while maintaining tolerance to self-proteins 1.

From the Research

Function of the Major Histocompatibility Complex (MHC)

The Major Histocompatibility Complex (MHC) plays a crucial role in the human immune system. The primary function of MHC molecules is to bind to peptide fragments derived from intracellular proteins and display them on the cell surface for recognition by T-cells [ 2 ]. This process enables the immune system to distinguish between self and non-self, allowing for the recognition and elimination of infected cells or foreign substances.

MHC Class I and Class II Molecules

MHC class I molecules are responsible for presenting endogenously synthesized peptides to cytotoxic T-cells [ 3 ], while MHC class II molecules present exogenously derived peptides to helper T-cells [ 4 ]. The binding of peptides to MHC molecules is a critical step in the initiation of an immune response.

Key Features of MHC Molecules

Some key features of MHC molecules include:

• The ability to bind to a wide range of peptides [ 2 ]
• The presence of glycosylation sites, which may play a role in immune function [ 5 ]
• The ability to internalize and recycle back to the cell surface, allowing for the exchange of peptide antigens [ 4 ]

Importance of MHC Molecules

MHC molecules are essential for the proper functioning of the immune system, and alterations in MHC expression or function can lead to immune-related disorders [ 2 ]. Understanding the structure and function of MHC molecules is crucial for the development of effective immunotherapies and vaccines [ 6 ].