A 24-year-old nurse comes to the office for his annual wellness visit that includes tuberculosis screening. The patient has no chronic medical conditions and does not have recent fever, cough, or other health changes. He receives an intradermal injection of tuberculin on the inner surface of his forearm. Two days later, he has a distinct area of induration 20 mm across at the injection site. Which of the following interactions is essential to the development of this patient's skin reaction?

Question

A 24-year-old nurse comes to the office for his annual wellness visit that includes tuberculosis screening.  The patient has no chronic medical conditions and does not have recent fever, cough, or other health changes.  He receives an intradermal injection of tuberculin on the inner surface of his forearm.  Two days later, he has a distinct area of induration 20 mm across at the injection site.  Which of the following interactions is essential to the development of this patient's skin reaction?

Quizplus · Accepted Answer

Eductional Objective: Tuberculin skin testing triggers a type IV delayed-hypersensitivity reaction in patients with previous infection due to the presence of primed, antigen-specific CD4 T lymphocytes.  These lymphocytes recognize tuberculin proteins displayed on antigen-presenting cells (APCs) and become activated following a costimulatory interaction between CD28 on the T cell and CD80/86 on the APC.

A 24-Year-Old Nurse Comes to the Office for His Annual