A radio-immunoelectrophoretic assay for human growth hormone.

A number of attempts have been made to measure the amount of growth hormone in human plasma or in extracts thereof. By using the tibia-line biological assay Gemzell (1959) and Forsman & Gemzell (1959) detected growth hormone in extracts from subjects with acromegaly or diabetes but not in extracts of normal plasma. Owing to the lack of sensitivity and specificity of biological assays for growth hormone no further attempts with these methods have been reported. The sulphation factor in serum has been used as an indication of human growth hormone (Daughaday, Salmon & Alexander, 1959; ALnquist & Falkheden, 1961), but despite its usefulness the values obtained are not direct measurements of the hormone. An immunological approach to the problem was provided by the work ofHayashida & Li (1958) and of Read & Stone (1958), who produced antiserum to purified human growth hormone in the rabbit. The reaction between growth hormone and its antibody has formed the basis of a number of assays for the hormone. Read & Stone (1958) and Read & Bryan (1960) have used the haemagglutination-inhibition technique for this purpose. Subsequent experience (cf. Read, Eash & Najjar, 1962; Grumbach & Kaplan, 1962) showed that it was subject to gross interference by plasma. However, Ehrlich & Randle (1962) obtained reproducible results with the method and were able to use it for comparative purposes in studying diabetes mellitus. The removal of non-specific inhibition by an extraction procedure has been reported by Dominguez & Pearson (1962), and the concentrations of growth hormone in normal adults were found to be less than 20,umg./ml. of serum. Methods based on the quantitative precipitin reaction (Li, Moudgal & Papkoff, 1960), complement fixation (Trenkle, Moudgal, Sadri & Li, 1961) and the precipitin reaction with '81I-labelled antibody (Greenspan, Cofell, Lew & Peng, 1962) do not appear to be subject to interference by plasma. However, the sensitivity of these methods is not adequate for the measurement of growth hormone in plasma. Greater sensitivity was achieved by Utiger, Parker & Daughaday (1962) by using im-