A 52-year-old man from rural Maharashtra presents with fever, weight loss, and acute mononeuritis multiplex affecting the left ulnar and right peroneal nerves. Serum creatinine is 1.8 mg/dL with mild proteinuria and hematuria. CT angiography of the abdomen shows microaneurysms in the renal and mesenteric arteries. A skin biopsy of a tender subcutaneous nodule is performed. Histopathology reveals necrotizing arteritis of medium-sized arteries with fibrinoid necrosis, mixed inflammatory infiltrate, and destruction of the internal elastic lamina (**C**). ANCA testing is negative. HBsAg is positive. Which of the following best explains why the structure marked **C** is destroyed in this patient's vasculitis, and what is the pathophysiologic consequence?