Linear IgA Bullous Dermatosis Pediatric

A 3-year-old boy presents with a 2-week history of recurrent blistering lesions on his lower abdomen and inner thighs. Examination reveals tense, fluid-filled bullae arranged in annular clusters around central crusts, producing a characteristic "string of pearls" appearance as marked **A** in the diagram. Direct immunofluorescence of perilesional skin shows linear IgA deposition along the basement membrane zone. Which of the following best describes the pathogenic mechanism underlying this clinical presentation?