What is the importance of MHC molecules in immune recognition?

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What is the importance of MHC molecules in immune recognition?

MHC molecules are the platform that makes immune recognition possible by showing peptide fragments on the cell surface for T cells to inspect. This is how the immune system distinguishes self from non-self. There are two main classes: Class I MHC is present on nearly all nucleated cells and presents peptides from inside the cell to CD8+ cytotoxic T cells; Class II MHC is on professional antigen-presenting cells and presents external, phagocytosed peptides to CD4+ helper T cells. When a T cell receptor recognizes a specific MHC–peptide complex, with the right co-stimulatory signals, it becomes activated and directs the appropriate response—killing infected or abnormal cells or helping B cells generate antibodies, with the development of immunological memory in time. Other functions listed—producing cytokines, recruiting neutrophils, or guiding red blood cell development—are mediated by cytokines, chemokines, and growth factors, not by presenting antigens via MHC.

MHC molecules are the platform that makes immune recognition possible by showing peptide fragments on the cell surface for T cells to inspect. This is how the immune system distinguishes self from non-self. There are two main classes: Class I MHC is present on nearly all nucleated cells and presents peptides from inside the cell to CD8+ cytotoxic T cells; Class II MHC is on professional antigen-presenting cells and presents external, phagocytosed peptides to CD4+ helper T cells. When a T cell receptor recognizes a specific MHC–peptide complex, with the right co-stimulatory signals, it becomes activated and directs the appropriate response—killing infected or abnormal cells or helping B cells generate antibodies, with the development of immunological memory in time.

Other functions listed—producing cytokines, recruiting neutrophils, or guiding red blood cell development—are mediated by cytokines, chemokines, and growth factors, not by presenting antigens via MHC.

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