Vogt-Koyanagi-Harada Syndrome

A 32-year-old woman of Hispanic descent presents with a 2-week history of severe bilateral eye pain, photophobia, and blurred vision. She reports preceding headache, tinnitus, and neck stiffness 1 week prior. Fundoscopy reveals bilateral optic disc hyperemia and multifocal serous retinal detachments. EDI-OCT confirms diffuse choroidal thickening. Over the following weeks, she develops the characteristic appearance marked **B** in the diagram—diffuse retinal pigment epithelium depigmentation with exposure of the underlying orange choroidal vasculature. She also notices whitening of her eyelashes and eyebrows, and patchy hair loss on her scalp. Which of the following BEST describes the underlying pathophysiology of the condition marked **B**?