CD8+ T cell–mediated destruction of pancreatic beta cells is a hallmark of which disease?

• A. Type 2 diabetes mellitus
• B. Type 1 diabetes mellitus
• C. Celiac disease
• D. Hashimoto thyroiditis

Answer: (B)

CD8+ T cells are killer cells that destroy target cells presenting specific peptides. In Type 1 diabetes mellitus, an autoimmune process targets the insulin-producing beta cells in the pancreatic islets. Autoreactive CD8+ T cells infiltrate the islets (insulitis) and kill beta cells via cytotoxic mechanisms, leading to loss of insulin production and an absolute insulin deficiency. This cell-mediated destruction is a defining feature of Type 1 diabetes, setting it apart from Type 2 diabetes, where the problem is primarily insulin resistance and gradual beta-cell dysfunction rather than direct immune destruction; celiac disease involves an autoimmune reaction against gluten affecting the intestinal mucosa; Hashimoto thyroiditis involves autoimmune attack on the thyroid gland, not pancreatic beta cells.