A 9-year-old boy has had fever and migrating polyarthralgia for 3 days. Examination shows a serpiginous rash. His left knee is swollen. Cardiac examination shows a 3/6 holosystolic murmur heard loudest at the apex. The mechanism responsible for this patient’s murmur is most immunologically similar to which of the following?
Anaphylaxis
Heparin-induced thrombocytopenia
Serum sickness
Tuberculin skin test
