Review Question - QID 210798

A 22-year-old woman presents to her primary care physician because she has been having severe pruritus on her left leg. She says the symptoms started 1 week ago after she went on a hiking trip with her friends. She wore shorts during the hike and felt as if something brushed her skin on the front of her leg just below the knee. She has no past medical history and no family history of autoimmune diseases. On physical exam, she has red pruritic papules and vesicles on her left leg. Which of the following mechanisms was most likely involved in the development of this patient's symptoms?