<prompt> Abatacept is -TNF alpha inhibitorInhibitor of co - stimulation of T cellsIL - I receptor antagonistMonoclonal antibody against IL - 6 receptor  <response>: Ans. is b i.e., Inhibitor of co-stimulation of T cells o Abatacept inhibits the co - stimulation of T cells by blocking CD28 - CD8086 interactions and also inhibits the function of antigen presenting cells by reverse signalling through CD80 and CD 86. 