We extracted gammaglobulins from the serum of 10 patients with insulin-dependent diabetes mellitus (IDDM) to investigate their effect on anterior pituitary hormone secretion using cultures of rat anterior pituitary cells. Three of the 10 patients also had the polyglandular autoimmune syndrome (PGA) type III with an isolated failure of anterior pituitary hormone secretion. The gammaglobulin from each of the 3 patients with PGA and an isolated failure of secretion of adrenocorticotropic hormone (ACTH), thyroid stimulating hormone (TSH) or gonadotropin inhibited the secretion of ACTH, TSH or gonadotropin in cultures of rat anterior pituitary cells. The gammaglobulins obtained from the other 7 patients with IDDM also showed an inhibitory or stimulatory effect on anterior pituitary hormone secretion in vitro. We postulate that some patients with IDDM, especially those with other endocrine autoimmune diseases, may have substances in their gammaglobulin fraction that can affect the secretion of anterior pituitary hormones.
(Internal Medicine 35: 686-692, 1996)