Bioassay and radioimmunoassay of lactogens in sera from children

Lactogen levels in sera from children have been determined using the Nb 2 lymphoma cell bioassay (BA) and conventional radioimmunoassay (RIA). Assays were done on samples obtained under basal conditions and after pituitary stimulation induced by insulin or arginine administration. There was a close correspondence between BA and RIA results ( r = 0.94; n = 43). The average ratio of the BA and RIA estimates of the lactogen levels (BA/RIA) was 0.86 ± 0.13 (mean ± SD) and 0.82 ± 0.17 for basal and stimulated conditions, respectively. The increased secretion of lactogens after pituitary stimulation was not found to be associated with a change in the BA/RIA ratio.