Autoimmunity to anterior pituitary cells and the pathogenesis of insulin-dependent diabetes mellitus.

An immunofluorescence study using unfixed cryostat sections of human pituitary glands was carried out on sera from patients with type-Ia (juvenile-onset) diabetes (61 recent onset, 48 longstanding). 63 of their selected high-risk first-degree relatives and 117 patients with type-Ib ("polyendocrine") diabetes were tested for comparison. Healthy controls included 48 sera from laboratory staff and students. Pituitary-cell antibodies were found in none of the controls, in 2% of patients with longstanding diabetes, in 16.6% of patients with diabetes of recent onset, and in 36.6% of genetically predisposed relatives with islet-cell antibodies in their sera (of whom 7 became diabetic during a 3-year follow-up period, 4 of them reacting with pituitary cells for 1-3 years before the onset of diabetes). Thus pituitary antibodies tended to disappear after onset of symptoms. Many of the sera reacted with multiple anterior-pituitary cell types. These findings suggest a wider involvement of the endocrine-organ system in the pathogenesis of insulin-dependent diabetes and are in accordance with clinical observations showing excess growth in prepubertal boys at onset of diabetic symptoms and with the results of experiments on virus-induced diabetes in mice. The connection of these pituitary antibodies with autoimmune lymphocytic hypophysitis is at present unknown.