This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'The most potent stimulator of naive T cells- \nSelect and explain. \nA. Mature dendritic cells, B. Follicular dendritic cells, C. Macrophages, D. B cell', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Mature B cells and T-cells before antigenic exposure are called naive B and T cells respectively.\n\nThe sequence of events in the activation of naive T cells :\n\nImmature dendritic cells in the epidermis are called Langerhans cells.\nThese immature dendritic cells (Langerhans cells) capture the antigen in the epidermis.\nAfter capturing the antigen, these cells secrete cytokines.\nThese cytokines cause loss of adhesiveness of Langerhans cells.\nLangerhans cells separate from each other and migrate to lymphatic vessels.\nIn a lymphatic vessel, maturation of Langerhans cells takes place.\nThen these mature Langerhans dendritic cells reach to naive T cells in the lymph nodes and present antigen to these cells and activate them.', 'role': 'assistant'}]