MHC Class II

MHC Class II

MHC (major histocompatibility complex) Class II molecules are found only on antigen-presenting cells and lymphocytes.

The antigens presented by class II peptides are derived from extracellular proteins (not cytosolic as in class I); hence, the MHC class II-dependent pathway of antigen presentation is called the endocytic or exogenous pathway.

Loading of MHC class II occurs by phagocytosis; extracellular proteins are endocytosed, ingested in lysosomes, and created by the class II MHC molecule prior to the molecule's migration to the cellular membrane.

Read more about MHC Class II:  Structure, Reaction To Bacteria, Synthesis, Genes

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