Fetal antigen 1 in healthy adults and patients with pituitary disease: Relation to physiological, pathological, and pharmacological GH levels

Immunohistochemical analysis of the distribution of human fetal antigen 1(F A1) in adult human tissues has demonstrated a strong association between FA 1 and (neuro)endocrine structures. In the anterior pituitary gland FA1 was colocalized with GH, and the present study was performed to evaluate a poss ible relationship between GH and FA1. FA1 and GH levels were measured durin g a 24-h period at 20-min intervals. In contrast to the known GH peaks duri ng 24-h sampling, there was no detectable FA1 peak. The FA1 responses to pl acebo were not significantly different from the responses to the combinatio n of pyridostigmine and GHRH. No significant difference was found between b asal FA1 (nanograms per ml) levels [median (minimum-maximum)] in healthy ad ults [n = 40; 28.6 ng/ml (12.5-72.0)], acromegalic patients [n = 11; 31.0 n g/ml (21.6-56.3)], and patients with GH deficiency [n = 22; 32.1 ng/ml (13. 4-108.7)]. FA1 levels were significantly reduced, in the six of seven acromegalic GH r esponders to octreotide, from [median (minimum-maximum)] 30.6 ng/ml (20.0-4 3.1) to 20.3 (13.9-30.2; P < 0.02). There was no significant change during placebo. FA1 levels were significantly increased compared with placebo valu es during 3 months of GH therapy. The increase in FA1 levels was significan tly higher than the change during placebo (P < 0.003). In conclusion, a common secretory and stimulatory pathway for FA1 and GH in healthy adults has been ruled out. However, we found that pharmacologicall y induced changes in GH levels during weeks to months had a corresponding d irect or indirect effect on FA1 levels in patients with GH deficiency or ac romegaly. However, a direct effect of octreotide on FA1 levels, independent of GH levels, has not been ruled out.