Autoimmunity And Self-Tolerance Practice Test

A 7-year-old girl is brought to the clinic with persistent oral thrush. Her history is significant for hypocalcemic seizures at age 2, which were attributed to hypoparathyroidism. On examination, she has vitiligo and signs of adrenal insufficiency. Laboratory studies show low serum calcium, high phosphate, and low parathyroid hormone levels. A genetic analysis is performed.

A self-reactive CD4+ T cell that has escaped central tolerance encounters a self-antigen presented by a renal tubular epithelial cell. This epithelial cell expresses MHC class II molecules but lacks the B7 co-stimulatory molecule (CD80/86).