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: Pathology
[{'content': 'Cell surface molecules involved in peripheral tolerance induction are \nSelect and explain. \nA. B7 and CD28, B. CD40 and CD40L, C. CD34 and CD51, D. B7 and CD3', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Immunological tolerance in peripheral lymphoid organs is called as peripheral tolerance. It requires signal to (interaction between CD28 and B7). CD28 molecules (co-stimulatory molecule) bind to their ligands-CD80 (B7-l) and/or CD86 (B7-2) and activates T-cell. If the antigen presented by cell do not bear CD28 ligand, a negative signal is delivered and cell become tolerant and anergic.', 'role': 'assistant'}]