Quantitative Observations on the Biological and Immunological Assays of Human Growth Hormone

Quantitative assays for growth, lactogenic and hemagglutination inhibiting activities were made on a number of crude and purified growth hormone preparations. Statistical comparisons between relative activities of different preparations revealed no differences in ratio of prolactin to growth hormone, the relationship being of the order of 1:10, on an estimated weight basis using sheep prolactin and tovine growth hormone as standards for comparison. Incubation of preparations with anti-human growth hormone antisera resulted in quantitative inhibition of both growth and lactogenic activities. The possible physiological and biochemical implications of this apparent inseparability of activities and constant ratio in current preparations of human growth hormone are discussed. (Endocrinology74: 366, 1964)