A 55-year-old woman presents with a 6-month history of progressive joint pain, morning stiffness lasting over an hour, and intermittent low-grade fevers. Physical examination reveals symmetric swelling and tenderness of her metacarpophalangeal and proximal interphalangeal joints, as well as subcutaneous nodules over the extensor surfaces of her elbows. Laboratory studies show elevated ESR, positive rheumatoid factor, and strongly positive anti–cyclic citrullinated peptide (anti-CCP) antibodies. Which of the following processes occurring in her affected joints best explains the pathogenesis of her disease?