Step 1

Immunology 4

A 18-month old boy is brought to the physician’s office by his parents for evaluation of recurrent nosebleeds. In the past year, he has had four respiratory infections and three episodes of otitis media. Past medical history is otherwise unremarkable, and he does not currently take any medications. His immunizations are up to date. He is at the 4th percentile for both height and weight. His vital signs are within normal limits. Cardiopulmonary examination shows no abnormalities. There are dry, scaly white lesions on his forehead, cheeks, and elbows.

Hematologic studies show the following:

  • Hemoglobin: 13.7 g/dL
  • Hematocrit: 43%
  • Mean corpuscular volume: 89 μm3
  • Leukocyte count: 10,000/mm3
  • Platelet count: 90,000/mm3
  • Partial thromboplastin time: 35 seconds
  • Prothrombin time: 15 seconds

Which of the following laboratory findings would most likely be present in this patient?

  • A) Decreased IFN-y
  • B) Decreased IgA
  • C) Increased IgE
  • D) Increased IgG
  • E) Increased IgM


Danielle Uayan


Dr. Ted O'Connell