A 28-year-old man with a history of seasonal allergies undergoes a tuberculin skin test. After 48 hours, a 12 mm indurated nodule develops at the injection site. The cellular infiltrate at this site is predominantly composed of which cells?
- A Mast cells and basophils
- B CD4+ T lymphocytes and macrophages ✓
- C Neutrophils and eosinophils
- D CD8+ cytotoxic T lymphocytes
Correct answer: B. CD4+ T lymphocytes and macrophages
Explanation
A positive tuberculin reaction is a classic delayed-type hypersensitivity (type IV) reaction mediated by sensitized CD4+ Th1 cells and macrophages recruited to the site. Mast cells and basophils drive type I immediate hypersensitivity, while neutrophils dominate acute suppurative inflammation. CD8+ T cells mediate cytotoxic type IV reactions, but tuberculin reactivity is CD4+ driven.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.