Development of a radioimmunoassay for adrenal specific protein: its measurement in biological fluids and tissues.

A radioimmunoassay for a new human adrenal specific protein (ASP) is described. The assay has a lower limit of detection of approximately 50 micrograms/l. The ASP extracted and purified from adrenal glands was used for standardization, radio-iodination and immunization of rabbits. Adrenal specific protein can be detected in normal human serum and plasma (240 +/- 80 and 190 +/- 60 micrograms/ml (means +/- S.D.) respectively), tissue levels were found in extracts of adrenal medulla, with appreciable amounts in the adrenal cortex, pituitary gland, seminal vesicle and testis, and low levels in all other tissues examined. The highest concentrations in biological fluids were found in seminal plasma and to a lesser extent in milk and menstrual fluid.