Reactivity of different LH and FSH standards and preparations in the World Health Organization matched reagents for enzyme-linked immunoassays of gonadotrophins

The immunoreactivity of various LH and FSH calibration standards and recombinant preparations in the enzyme-linked immunoassay (EIA) systems for gonadotrophins developed for the Special Programme of Research in Human Reproduction of the World Health Organization (WI-IO) were compared. The preparations tested included three LH and two FSH pituitary standards (calibrated against LH 80/552 and 68/40 and FSH 78/549 respectively) provided with the EIA or radioimmunoassay WHO matched reagent kits, the pituitary preparation LER-907, and recombinant human LH (rhLH) and FSH (rhFSH), Simultaneous curve fitting of the EIA dose-response curves revealed no significant differences among the slopes generated by the WHO LH standards and LER-907; in contrast, no parallelism was found between the curves of rhLH and the pituitary-derived LH standards. No significant differences were found among the slopes of the curves elicited by the pituitary and recombinant FSH preparations. Each LH preparation exhibited a high degree of charge heterogeneity. Considerable variations in charge isoform distribution among the WHO LH standards, rhLH and LER-907 mere also evident. In contrast, the FSH preparations were less heterogeneous and exhibited minor differences in charge distribution. Despite the existing differences in charge isoform distribution, all the pituitary-derived preparations as well as rhFSH seem appropriate for using as calibration standards in this particular ELA system.