Antibodies to pituitary surface antigens during various pituitary disease states.

Autoantibodies to cell surface antigens of human somatotropinoma (ASAS), human prolactinoma (ASAP) and rat adenohypophysis (ASARA) were assayed in the serum of patients with pituitary diseases associated with GH deficiency (GHD), such as pituitary dwarfism and primary empty sella syndrome (ESS), and in the serum of patients with hyperprolactinaemia of different etiologies: idiopathic hyperprolactinaemia, prolactinoma and ESS. The investigation was carried out with a cellular variant of an ELISA. Among children with GHD, the highest percentage of antibody-positive patients was found in the group with idiopathic isolated GHD (89% of ASAS(+) patients and 30% of ASARA(+) patients vs 33.3% and 0% respectively in the group with idiopathic combined pituitary hormone deficiency, and 33.3% and 9% in patients with pituitary hypoplasia associated with isolated GHD or combined pituitary hormone deficiency). Among hyperprolactinaemic patients, the highest ASAP and ASARA frequency was observed in patients with idiopathic hyperprolactinaemia (67.7% and 41.9% respectively) where it was twice as high as in the group of patients with prolactinoma. The proportion of ASAS(+) and ASARA(+) did not differ significantly between the groups of patients with ess with or without GHD. Similarly, there was no significant difference between the number of ESS ASAP(+) and ASARA(+) patients with or without hyperprolactinaemia. The data obtained suggested that autoimmune disorders may be primary, and responsible, at least in part, for pituitary dysfunction in the cases of idiopathic isolated GHD and idiopathic hyperprolactinaemia. At the same time, the autoimmune disorders in the patients with prolactinoma or ESS are probably secondary to the organic pituitary lesion and their significance in the development of the pituitary dysfunction is obscure.

Involvement of proteolytic enzymes in the lipotropic effect of the pituitary polypeptide hormones.

The influence of proteinase inhibitors on the lipolytic effect of the pituitary polypeptide hormones and epinephrine in an isolated adipose tissue of rabbits and rats has been studied. Neither of proteinase inhibitors changed the basal rate of lipolysis. Trasylol, a serine proteinase inhibitor, suppressed completely growth hormone (GH) effect and partially reduced the effect of adrenocorticotropin (ACTH) and beta-lipotropin (beta-LPH) but did not change the effect of epinephrine. Bacitracin proved ineffective with regard to the effect of polypeptide hormones. Pepstatin, an acid proteinase inhibitor, partially blocked the stimulation of lipolysis by ACTH without affecting the effect of GH and beta-LPH. The influence of proteinase inhibitors on the ACTH effect in rat adipose tissue was similar to that found in rabbit tissue. The Trasylol-induced inhibition of the hormone-stimulated lipolysis decreased to a considerable extent after GH or ACTH incubation with rabbit plasma or partial GH digestion with pepsin. This decrease was not observed when plasma serine proteinases were blocked during GH incubation with plasma. The results demonstrate an involvement of some proteolytic enzymes in the realization of the polypeptide hormone lipolytic effect and permit to suppose the requirement of preliminary activation of the hormones by means of proteolytic modification.