Properties of human gonadotrophins eluted from human corpus luteum and mouse luteoma LH-HCG receptors

Studies were performed to try to determine if gonadotrophins are altered during their interaction with tissue receptors. Immunologic, electrophoretic and binding properties of lactoperoxidase labelled [125I]HLH and [125I]HCG were examined before and after elution from mouse lutomea and human corpora lutea receptor preparations. The anti-HCG used in these studies at a 1:10 000 dilution precipitated 92% of a freshly iodinated [125I]HCG preparation. Receptor eluted [125I]HCG, derived from the same batch of labelled ligand, was virtually quantitatively precipitated by the same dilution of anti-HCG. [125I]HCG eluted from the human corpus luteum was electrophoretically more homogeneous when compared to its heterogenous parent labelled preparation and migrated to a position similar to that of native HCG. In Ouchterlony double diffusion experiments against anti-HCG antiserum, corpus lutheum eluted [125I]HCG and [125I]HLH showed immunologic identity with each other as well as with native HCG and HLH. Receptor eluted [125I]HCG from the mouse luteoma, following in vivo administration via tail vein injection or after incubation in vitro with labelled hormones, was immunologically indistinguishable from native HCG. The electrophoretic mobility of HCG was retarded when HCG was added to extracts of mouse luteoma, liver and kidney. Eluates of mouse luteoma, applied to Bio-Gel columns previously equilibrated with [125I]HCG showed the ability to concentrate [125I]HCG in the high molecular weight column fractions. (author)