<prompt> Abatacept is a new drug approved for:SLERheumatoid arthritisSjogren syndromeScleroderma  <response>: Ans. B Rheumatoid arthritisRef: Harrison 18th2748Abatacept 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 APC2. Co-stimulatory signal: Interaction of CD 28 of T-cells with CD-8086 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. 