This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Chemotherapy, Subject name: Pharmacology
[{'content': 'Abatacept is a \nSelect and explain. \nA. IL1 antagonist, B. INFa neutralizing drug, C. Immunosuppressent, D. Fusion protein', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Abatacept is a fusion protein consisting of CTLA4 and the Fc poion of IgG1. It inhibits T cell activation by competitively inhibiting the costimulation of T cells that results from an interaction of T cell-expressed CD28 and CD80/86 expressed by antigen-presenting cells. It can be used with or without methotrexate, although its efficacy is greater as cotherapy with methotrexate. It has a positive effect on signs and symptoms of RA and also retards progressive bone damage.', 'role': 'assistant'}]