Antigen presenting cells Concepts Endogenous antigens: antigens produced within cells Exogenous antigens: antigens internalized by endocytosis Ag capturing-------Endocytosis Phagocytosis Pinocytosis Receptor-mediated endocytosis Ag processing and Ag presentation a protein antigen be degraded into peptides by a sequence of events The degraded peptides associate with MHc molecules and the peptides-MHC molecule complexes are transported to the membrane, where they are displayed.I. Antigen presenting cells ◼ Concepts Endogenous antigens: antigens produced within cells Exogenous antigens: antigens internalized by endocytosis Ag capturing-------Endocytosis Phagocytosis Pinocytosis Receptor-mediated endocytosis Ag processing and Ag presentation A protein antigen be degraded into peptides by a sequence of events The degraded peptides associate with MHC molecules, and the peptides-MHC molecule complexes are transported to the membrane, where they are displayed