Abatacept Mechanism — SCE Rheumatology MCQ
Instant feedback + full explanation. One question, done properly.
Educational content. Not a substitute for clinical judgement or local policy.
Reveal the answer and explanation
Correct answer: D — CD80/CD86 binding to CD28
Abatacept is a fusion protein comprising the extracellular domain of CTLA-4 linked to a modified human IgG1 Fc region. It binds CD80 and CD86 on antigen-presenting cells, preventing their interaction with CD28 on T lymphocytes. This blocks the second, co-stimulatory signal required for full T-cell activation. JAK inhibition is the mechanism of targeted synthetic DMARDs such as baricitinib and upadacitinib. IL-6 signalling is inhibited by agents such as tocilizumab, whereas adalimumab and other TNF inhibitors prevent TNF-mediated signalling. Rituximab targets CD20 and depletes B cells. The original answer was correct, but its markedly longer wording cued the answer; unsupported claims about preferential use in COPD, recurrent infection and a favourable safety profile were also removed.
Reference: ORENCIA (abatacept) Summary of Product Characteristics, section 5.1 Pharmacodynamic properties—Mechanism of action, text revised 2024. https://www.medicines.org.uk/emc/product/10244/smpc