A 23-year-old woman who was recently diagnosed with rheumatoid arthritis comes to the physician for a follow-up examination. Two months ago, she began treatment with adalimumab, which binds with tumor necrosis factor-a. The patient says that her symptoms have not improved. Physical examination shows mild swelling of the joints of the wrists, hands, ankles, and feet. Which of the following immune system components is most likely contributing to this patient's symptoms?
A) IgA
B) IgE
C) Interleukin-1 (IL-1)
D) IL-4
E) Vascular endothelial growth factor