Splenic macrophages and dendritic cells play a crucial role in the immune response, particularly in their ability to process and present antigens. These cells are strategically located within the spleen, which is a key organ for filtering the blood and facilitating immune surveillance. When they encounter pathogens or foreign substances, they are capable of taking up these antigens and processing them into smaller peptide fragments.
After processing, dendritic cells and macrophages present these peptide fragments on their surface bound to major histocompatibility complex (MHC) molecules. This presentation is essential for stimulating T cells, as T cells recognize the complex of antigens and MHC molecules. In addition, through various cytokines and co-stimulatory signals, these antigen-presenting cells can help activate B cells, which are responsible for producing antibodies.
This dual role of activating both T and B cells explains why the correct answer emphasizes the importance of splenic macrophages and dendritic cells in antigen uptake and the stimulation of adaptive immune responses. The activation of T and B cells leads to a tailored and effective immune response that is crucial for combating infections and establishing immunological memory.