Section: USMLE

59) A 12-year-old girl has a temperature of 102.5 F and a sore throat. Two days later, she develops a diffuse erythematous rash and is taken to her pediatrician. On physical examination, there is circumoral pallor, and an erythematous rash with areas of desquamation is noted. The myocardial damage that can follow this infection is produced in a manner similar to the damage associated with which of the following disorders?

1. Atopic allergy
2. Systemic lupus erythematosus
3. Contact dermatitis
4. Graft-vs-host disease
5. Graves disease
6. Idiopathic thrombocytopenic purpura
7. Myasthenia gravis
8. Rheumatoid arthritis
9. Serum sickness

This is a case of rheumatic fever, which is an immunologically mediated sequela to Streptococcus pyogenes pharyngitis. It is a type II cytotoxic hypersensitivity, involving antibodies that bind to cardiac tissue, activate complement, and thereby cause cell destruction. It is therefore most similar to idiopathic thrombocytopenic purpura, which is also a form of type II cytotoxic hypersensitivity, in this case mediated by antibodies against platelets producing complement fixation and causing the clotting dyscrasia.

Atopic allergy is a form of type I hypersensitivity, mediated by IgE antibodies and basophils and mast cells.

Contact dermatitis is a form of type IV hypersensitivity mediated by T cells and macrophages.

Graft-vs-host disease is a form of type IV hypersensitivity mediated by T cells and macrophages.

Graves disease is a form of type II hypersensitivity, but it is NOT cytotoxic in its action. Instead, antibodies to the TSH receptors on thyroid cells cause overstimulation of the gland and its eventual exhaustion.

Myasthenia gravis is a form of type II hypersensitivity, but NOT of the cytotoxic variety. In this case, antibodies to the acetylcholine receptors on neurons diminish neurotransmission.

Rheumatoid arthritis is a form of type III hypersensitivity, caused by immune complex deposition in joints and subsequent activation of complement.

Serum sickness is a form of type III hypersensitivity, caused by immune complex deposition.

Systemic lupus erythematosus is a form of type III hypersensitivity, caused by immune complex deposition.