Abstract
We have shown that the ratio of bioactive to immunoreactive LH increases during puberty. To test whether this change is in the immuno- or biopotency of LH, we tested dose-response characteristics in both assays. Results: 1) In the bioassay (RICT), the dose-response characteristics of basal and GnRH-stimulated plasma samples from pubertal (PUB) and adult subjects and the LER-907 and I-1 standards were parallel; prePUB basal and GnRH-stimulated samples were less steep (-0.75 v. -1.00, p<0.05). Turner syndrome samples had slopes 8% greater. 2) Using an RIA with a bioactive 125I-hLH and NIADDK antiserum we found that the dose-response relationship of plasma I-LH changes through puberty. The logit-log transformed dose-response curve for LER-907 was less steep than I-1 (-0.73 v. -1.05, p<0.05); potency estimates at the extremes of the standard curves differed by a factor of 1.7. There was no difference in slopes before and after GnRH infusion, but 7/14 prePUB samples, 3/14 PUB and 0/15 adult were parallel to LER-907, while 1/14 prePUB, 6/14 PUB and 12/15 adult were parallel to I-1. Turner syndrome samples had slopes similar to prePUB samples (-0.74 v. -0.79, NS).
Changing LH RIA dose-response characteristics is the principal factor in the changing ratio of bioactivity to immuno-reactivity during puberty. This may reflect the structural heterogeneity of LH.
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Burstein, S., Schaff-Blass, E. & Rosenfield, R. LH RIA DOSE-RESPONSE CHARACTERISTICS CHANGE DURING PUBERTY. Pediatr Res 18 (Suppl 4), 164 (1984). https://doi.org/10.1203/00006450-198404001-00428
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DOI: https://doi.org/10.1203/00006450-198404001-00428