A 65-year-old woman is enrolled in a clinical trial to test a new medication for rheumatoid arthritis. The patient's condition has been poorly controlled despite prolonged treatment with multiple disease-modifying antirheumatic drugs. The new medication is a CTLA4-Ig fusion protein that prevents CD28 from binding to CD80/86 on antigen-presenting cells. A month after treatment begins, the patient reports a significant reduction in joint pain and stiffness. Laboratory results reveal reduced levels of C-reactive protein and IL-2. Which of the following is the most likely underlying cause of this patient's treatment response?

Question

A 65-year-old woman is enrolled in a clinical trial to test a new medication for rheumatoid arthritis.  The patient's condition has been poorly controlled despite prolonged treatment with multiple disease-modifying antirheumatic drugs.  The new medication is a CTLA4-Ig fusion protein that prevents CD28 from binding to CD80/86 on antigen-presenting cells.  A month after treatment begins, the patient reports a significant reduction in joint pain and stiffness.  Laboratory results reveal reduced levels of C-reactive protein and IL-2.  Which of the following is the most likely underlying cause of this patient's treatment response?

Quizplus · Accepted Answer

Eductional Objective: Abatacept, a disease-modifying antirheumatic drug, is a fusion of CTLA4 with the Fc portion of IgG.  CTLA4 binds to CD80/86 on antigen-presenting cells, which prevents CD80/86 from binding to CD28 on T cells.  This reduces T cell costimulation and leads to anergy, which reduces inflammation.

A 65-Year-Old Woman Is Enrolled in a Clinical Trial to Test