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


METHODS
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).


METHODS
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.
De Bellis
Annamaria
A
Chair of Endocrinology, Department of Clinical and Experimental Medicine and Surgery F. Magrassi and A. Lanzara - Second University of Naples, 80131, Naples, Italy. annamaria.debellis@unina2.it
Bizzarro
Antonio
A
Perrino
Silvia
S
Coronella
Concetta
C
Conte
Marisa
M
Pasquali
Daniela
D
Sinisi
Antonio Agostino
AA
Betterle
Corrado
C
Bellastella
Antonio
A
D000328:Adult; D001323:Autoantibodies / Q000276:immunology*; D001327:Autoimmune Diseases / Q000276:immunology*; D004700:Endocrine System Diseases / Q000276:immunology*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods; D019382:Human Growth Hormone / Q000172:deficiency*; D006801:Humans; D008297:Male; D010902:Pituitary Gland / Q000276:immunology; D010907:Pituitary Hormones / Q000276:immunology*; D011388:Prolactin / Q000276:immunology
D001323:Autoantibodies; D010907:Pituitary Hormones; D019382:Human Growth Hormone; D011388:Prolactin