Anti-PIT-1 antibody syndrome; a novel clinical entity leading to hypopituitarism.

Various hypothalamic-pituitary diseases cause hypopituitarism. Inflammation related to autoimmunity also causes hypopituitarism. Hypophysitis is a representative disease caused by autoimmunity. Generally, anterior pituitary hormones are non-specifically impaired in this condition, but specific hormone defects have been reported in some cases. Anti-PIT-1 (pituitary-specific transcription factor 1) antibody syndrome is a novel clinical entity that presents an acquired combined pituitary hormone deficiency characterized by a specific defect in growth hormone, prolactin, and thyroid-stimulating hormone. Circulating anti-PIT-1 antibody along with various autoantibodies are detected with multiple endocrine organopathy, meeting the definition of autoimmune polyglandular syndrome. Mechanistically, cytotoxic T lymphocytes that specifically react with PIT-1 protein play an important role in the development of this syndrome.