{"knowledge_schema": {"broad_category": "Immunology \u2192 Cell Biology \u2192 T Cell Function", "refinement": "This problem focuses on the mechanisms of T cell activation and the role of antigen presentation in the immune response.", "specific_scope": "The question specifically addresses how T cells can be engineered to present antigens, which is traditionally a function of other immune cells like dendritic cells and macrophages.", "goal": "Identify the appropriate receptor that would enable T cells to function as antigen-presenting cells."}, "summary": "This question explores the potential for engineering T cells to act as antigen-presenting cells, a role typically fulfilled by dendritic cells and macrophages. The focus is on identifying a receptor that would facilitate this function. The candidates include various co-stimulatory and major histocompatibility complex (MHC) molecules. The goal is to determine which receptor, among the options provided, would enable T cells to present antigens effectively."}