Final answer:
Macrophages and dendritic cells are key in connecting innate and adaptive immunity, as they act as phagocytes that engage in antigen presentation, leading to T cell activation.
Step-by-step explanation:
Macrophages and dendritic cells play a crucial role in bridging the innate immune responses with adaptive immunity. These are phagocytes that ingest and kill pathogens, and are responsible for bringing antigens to regional draining lymph nodes to initiate the adaptive immune response.
Whereas macrophages are found in the skin and mucosal surfaces, dendritic cells are particularly efficient in antigen presentation to T cells. This interaction is pivotal for the activation of naive T cells and the subsequent adaptive immune response. B cells also present antigens to T cells, although they are not phagocytes themselves but play a primary role in antibody production.