Final answer:
Antigens from digested pathogens are presented on the surface of antigen-presenting cells attached to Major Histocompatibility Complex (MHC) molecules.
Step-by-step explanation:
Antigens are generated following phagocytosis when a pathogen or extracellular antigen is internalized by an antigen-presenting cell like a dendritic cell and placed into a vesicle. Once the pathogen is engulfed, a process takes place in which proteases break down the pathogens for antigen processing. The digested fragments are then presented on the cell surface attached to Major Histocompatibility Complex (MHC) molecules. It is this combination of an antigen fragment with an MHC molecule that is then recognized by T cells, initiating an adaptive immune response.
Antigens are attached to the surfaces of microorganisms after phagocytosis. When pathogens are digested by lysosomes in antigen-presenting cells like macrophages and dendritic cells, the digested pathogen material is chopped up and attached to the surfaces of microorganisms, which are then recognized by the immune system as foreign.