Final answer:
The sequence of events in antigen processing for presentation with MHC II molecules involves internalization, processing, and presentation of foreign antigens on the surface of antigen-presenting cells, allowing T cells to recognize and mount an immune response.
Step-by-step explanation:
The process of antigen processing and presentation involves a series of steps where a peptide being presented by MHC II molecules is recognized by T cells. Antigens are taken into the antigen-presenting cells (APCs), processed into smaller fragments, and presented on the surface of APCs in association with MHC II molecules. When foreign antigens are processed, they interact with MHC II molecules, and this complex is then brought to the surface via transport vesicles, where T cell receptors can recognize them.
MHC II molecules are predominantly found on specialized cells such as macrophages, dendritic cells, and B cells. The complete processing involves the digestion of antigens, incorporation into the endomembrane system, and expression on the surface of APCs for recognition by T cells. Once the immunodominant epitopes are displayed within the antigen-binding cleft of the MHC II on the cell surface, they can stimulate the corresponding T cells, leading to adaptive immune responses.