Characterization of antipituitary antibodies targeting pituitary hormone‐secreting cells in idiopathic growth hormone deficiency and autoimmune endocrine diseases

Abstract

Objective In order to investigate whether somatotrophs are the target of antipituitary antibodies (APA) in adult patients with growth hormone deficiency (GHD), we studied the sera of 37 APA positive patients. Patients Patients were grouped as follows: nine patients with APA at high titre (> 1 : 8) affected by apparently idiopathic GHD; four of them (group 1a) with isolated GHD diagnosed during childhood and five with GHD diagnosed during adulthood associated with autoimmune endocrine diseases (group 1b), and 28 patients with autoimmune endocrine diseases without pituitary impairment, previously found positive for APA at low titre (1 : 8, group 2). Measurements APA were evaluated by a four-layer double indirect immunofluorescence technique. Results In group 1a patients, APA immunostained exclusively GH-producing cells. In group 1b patients, APA were directed not only to GH-but also to other pituitary hormone-producing cells. In group 2 patients, APA were directed selectively to PRL-producing cells and rarely to some GH-producing cells. Conclusions In the present study, we demonstrated that GH-secreting cells are the target of the autoimmune reaction in autoimmune GHD and that the immunostaining of only the somatotrophs is typical of isolated GHD. In contrast, the finding of diffuse staining of APA indicates the need to search for other autoimmune diseases. Finally, the presence of APA at low titre directed against PRL-secreting cells in patients with autoimmune endocrine diseases in the absence of pituitary impairment, seems to be only a nonspecific marker of pituitary autoimmunity. A longitudinal study would be useful to clarify the relationship between the different pituitary cell involvement and the natural history of pituitary dysfunction in autoimmune hypophysitis.

Pituitary autoantibodies in autoimmune polyendocrine syndrome type 1

“…Double-staining for pituitary hormones revealed a partial colocalization with GH-producing cells, somatotrophs. Recent publications suggest that Aabs against somatotrophs, when present in high titers, may be considered a good diagnostic marker for autoimmune forms of GH-deficiency (33,34).…”

Antipituitary antibodies after traumatic brain injury: is head trauma-induced pituitary dysfunction associated with autoimmunity?

“…Although the antibodies against neurons have been demonstrated in injured animal studies, investigations regarding the occurrence of antipituitary antibodies (APAs) in patients with TBI are lacking in the literature. However, these antibodies have been detected in patients with selective idiopathic hypopituitarism, particularly in those with GH deficiency (9,10) and in adults with autoimmune endocrine diseases (11)(12)(13).…”

Antipituitary Antibodies in Dutch Patients with Idiopathic Hypopituitarism

“…Also, antibodies against PRL-secreting cells have been frequently observed in different forms of pituitary autoimmune involvement without clinical and biochemical modification of PRL secretion [34]. …”

“…The sera were tested in a blinded manner without the investigator performing the immunofluorescence knowing the clinical diagnosis of the respective patients. Antibodies against single pituitary hormone-producing cells were determined by a four-layer double-immunofluorescence technique as previously described [33, 34]. …”