A 2-year-old boy is brought to the emergency department due to wheezing and difficulty breathing. The patient had been trick-or-treating with his parents and ate several packs of candy containing peanuts. After he receives an intramuscular epinephrine injection, his symptoms resolve. At a follow up appointment, an allergy specialist places droplets of various allergens on the patient's skin and punctures the epidermis at each site. After 15 minutes, the skin at the site with peanut extract is erythematous with a raised, itchy bump that improves by the time the family leaves the office. Four hours later, the parents notice a hard, red swelling at the puncture site. Which of the following is most likely involved in this secondary reaction?

Question

A 2-year-old boy is brought to the emergency department due to wheezing and difficulty breathing.  The patient had been trick-or-treating with his parents and ate several packs of candy containing peanuts.  After he receives an intramuscular epinephrine injection, his symptoms resolve.  At a follow up appointment, an allergy specialist places droplets of various allergens on the patient's skin and punctures the epidermis at each site.  After 15 minutes, the skin at the site with peanut extract is erythematous with a raised, itchy bump that improves by the time the family leaves the office.  Four hours later, the parents notice a hard, red swelling at the puncture site.  Which of the following is most likely involved in this secondary reaction?

Quizplus · Accepted Answer

Eductional Objective: The late phase of dermatologic type I hypersensitivity reactions manifests as an indurated skin lesion hours after exposure to the allergen due to local tissue damage caused by major basic protein released from eosinophils.  In contrast, type IV hypersensitivity reactions develop over days because of the time needed to produce a cell-mediated immune response.

A 2-Year-Old Boy Is Brought to the Emergency Department Due