This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunomodulatory: DMARDS, Monoclonal Antibodies, Subject name: Pharmacology
[{'content': 'Abatacept is a new drug approved for: \nSelect and explain. \nA. SLE, B. Rheumatoid arthritis, C. Sjogren syndrome, D. Scleroderma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (B) Rheumatoid arthritis(Ref: Harrison 18th/2748)Abatacept is a co-stimulation inhibitor. Two signals are required for activation of T-cells:1. Main signal: Interaction of T-cell receptor (TCR) with MHC of antigen presenting cells (APC)2. Co-stimulatory signal: Interaction of CD 28 of T-cells with CD-80/86 of APC.When both signals are present, T-cell gets activated. Abatacept acts by blocking the co-stimulatory signal and prevents activation of T-cells. It is approved for treatment of Rheumatoid arthritis.', 'role': 'assistant'}]