Endocrine Abstracts

Lymphocytic hypophysitis is a rare endocrine autoimmune disorder. Principal laboratory markers for diagnosis are antipituitary antibodies (APA). So far there are no standardized methods for the detection of APA and it is not completely clear which antigens are they targeted to as well. At present the indirect immunofluorescence technique is commonly used for their detection. For this purpose cryostat sections of pituitary gland are used. Commercially accessible sections are acquired from primate pituitary glands, especially from baboons.

Design: The aim was to compare the results of APA detection in human sera using both baboon and human pituitary frozen sections in the same immunofluorescence system. A total of 138 sera of patients treated for both autoimmune thyroid disease and diabetes mellitus type 1 were evaluated for the presence of APA using both antigens. No patient had clinical signs of hypopituitarism.

Methods: APA were assayed by indirect immunofluorescence using sections of monkey anterior pituitary (Euroimmune AG) and freshly frozen human pituitary sections (from autopsy of person with blood group 0, Rh−). No dilution of investigated sera was used.

Results: From 138 patients 5 patients were APA positive using monkey sections. None of them was APA positive with human pituitary sections.

Conclusion: The difference between human and primate sections can be possibly caused by the presence of human anti-animal antibodies and this false positivity can increase the number of positive results in screening. The methods of APA detection are still to be standardized.