||Present on almost all nucleated cells including platelets.
||Have a restricted tissue distribution and are mainly found on macrophages, dendritic cells, B cells, and other antigen-presenting cells.
||MHC class I proteins are encoded by the HLA-A, HLA-B, and HLA-C genes.
||The genes encode MHC Class II proteins reside in the HLA-D region.
||Nature of the antigen presented
||Antigens presented by MHC class I molecules are of endogenous origin.
||Antigens presented by MHC class II molecules are derived from extracellular proteins.
||Cytosolic proteins; are sample peptides generated within the cell or those that may enter cytosol from phagosomes.
||Class II molecules sample peptides outside the cell such as lysosomal proteins mostly internalized from the extracellular environment.
||Enzymes involved in peptide generation
||Endosomal and lysosomal proteases
||Peptide loading of MHC
||Specialized vesicular compartment
||Includes the ER transporter associated with antigen processing (TAP1/2), tapasin, the oxidoreductase ERp57, and the chaperone protein calreticulin.
||Chaperones in ER; invariant chain in ER, Golgi and MHC Class II compartment/Class II vesicle
||They are recognized by CD8 co-receptors through the MHC Class I 2 subunit.
||They are recognized by CD4 co-receptors through 1 and 2 subunits.
||Receptor T cell
||Present antigens to CD8+T cells.
||Present antigens to CD4+T cells.
||MHC class I molecules consist of one membrane-spanning chain produced by MHC genes and one chain produced by the 2-microglobulin gene.
||MHC class II molecules consist of two membrane-spanning chains, which are produced by MHC genes.
||Building amino acids
||Possess 8-10 amino acids.
||Possess 13-18 amino acids.
||Peptide binding domains
||1 and 2 are peptide-binding domains.
||1 and 1 are peptide-binding domains.
||Has no invariant chain.
||Has an invariant chain.
||The presence of abundant antigens target cell for destruction.
||The presences of foreign antigens induce antibody production.
||Serology and mixed lymphocyte reaction