Characterization of specific antisera to native human luteinizing hormone.

Antisera against highly purified native hLH (10 000 IU/mg = 0.5 mg hLH/mg protein) were raised in 4 rabbits. The antisera were invariably of high titre and high avidity. They were purified by affinity chromatography on a column with hCG-Sepharose 4 B. Before and after adsorption the antisera were tested in a double antibody radioimmunoassay. Before adsorption hCG cross-reacted in all antisera, but in none were the inhibition curves identical. No such cross-reaction remained after the affinity chromatography. These purified antisera made it possible to develop highly specific and sensitive assays for measuring native hLH. We conclude from studies of the effect of native glycoprotein hormones and their subunits that there are probably differences in the antigenic sites of the complete hLH molecule and in the isolated beta-subunit of hLH. The investigation also indicates that even highly purified preparations of hTSH may be contaminated with hLH and that the preparations of hLH-subunits may contain a certain amount of the native hormone.