Binding of HLH and HCG by human corpus luteum: an in vitro study

The ability of human luteal tissue to bind HLH was studied. The tissue was obtained from patients subjected to gynecological operations intended to correct other than ovarian lesions. HLH iodinated with carrier-free 125I according to the Greenwood method was used. This material has a relatively low specific radioactivity (7-20 microCi/micrograms); therefore the biological characteristics of the hormone were expected to remain intact. The 90% binding point was estimated at 37 degrees C after 5 minutes. Inhibition experiments with HLH and HCG had a characteristic effect, even those with FSH and ovine prolactin indicated a significant interference with the bound hormone. Scatchard plots demonstrated large variability in the number of binding sites and relatively modest variability of constant (Kd).