A 40 year-old woman presented to the dermatology clinic with frank, fluid filled, pruritic blisters on her forearms, hands, wrists, and legs. She reports that last week while working in her garden, she was exposed to poison ivy plants. You noticed vesicles and flaccid bullae in a linear configuration on the involved areas. Which of the following immunopathogenic mechanisms is most likely to be the cause of this skin disease?