A 6-year-old girl from rural Maharashtra presents with recurrent oral candidiasis, hypocalcemia (corrected calcium 6.8 mg/dL), and hyponatremia. Investigations show elevated parathyroid hormone and elevated ACTH with low cortisol. Genetic testing reveals a homozygous mutation in the AIRE gene. The process marked **D** in the thymic maturation diagram (negative selection) is impaired in this patient. Which of the following best explains the pathophysiology of her autoimmune manifestations?