Final answer:
Professional antigen-presenting cells include macrophages, dendritic cells, and B cells, which are unique in their capability to present antigens with MHC class II molecules to T cells, triggering an immune response.
Step-by-step explanation:
Professional antigen-presenting cells include macrophages, dendritic cells, and B cells. These cells are capable of processing and presenting antigens in association with MHC class II molecules to T cells, a critical function in the immune response.
Macrophages are very effective phagocytic cells that engulf pathogens or worn-out cells and serve as APCs for other components of the immune system. Dendritic cells are present in various tissues and are adept at processing antigen material to induce an immune response. B cells, before activation and differentiation, also function as APCs, helping to initiate a targeted immune response against pathogens.
Importantly, only these professional APCs have the ability to present antigens with the express purpose of activating T cells, setting them apart from other cells that may present antigens in association with MHC class I molecules.