The pituitary-specific transcriptional factor-1 (PIT-1, also known as POU1F1), is an essential factor for multiple hormone-secreting cell types. A genetic defect in the PIT-1 gene results in congenital growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone (TSH) deficiency. Here, we investigated 3 cases of adult-onset combined GH, PRL, and TSH deficiencies and found that the endocrinological phenotype in each was linked to autoimmunity directed against the PIT-1 protein. We detected anti–PIT-1 antibody along with various autoantibodies in the patients’ sera. An ELISA-based screening revealed that this antibody was highly specific to the disease and absent in control subjects. Immunohistochemical analysis revealed that PIT-1–, GH-, PRL-, and TSH-positive cells were absent in the pituitary of patient 2, who also had a range of autoimmune endocrinopathies. These clinical manifestations were compatible with the definition of autoimmune polyendocrine syndrome (APS). However, the main manifestations of APS-I — hypoparathyroidism and Candida infection — were not observed and the pituitary abnormalities were obviously different from the hypophysitis associated with APS. These data suggest that these patients define a unique “anti–PIT-1 antibody syndrome,” related to APS.
Masaaki Yamamoto, Genzo Iguchi, Ryoko Takeno, Yasuhiko Okimura, Toshiaki Sano, Michiko Takahashi, Hitoshi Nishizawa, Anastasia Evi Handayaningshi, Hidenori Fukuoka, Maya Tobita, Takatoshi Saitoh, Katsuyoshi Tojo, Atsuko Mokubo, Akio Morinobu, Keiji Iida, Hidesuke Kaji, Susumu Seino, Kazuo Chihara, Yutaka Takahashi
Patients’ sera detected natural form of PIT-1 by immunohistochemistry, and the antibodies were of IgG1 and IgG3 subtypes.