Immunologic Cross-reaction Between Human Chorionic Gonadotropin and Human Pituitary Gonadotropin

Abstract

The capacity of human pituitary gonadotropin (NIH-HPG-UE) to absorb antibodies to HCG was measured in 7 experiments utilizing 2 rabbit and 1 sheep anti-HCG preparations. Maximum estimates of the degree of immunologic cross-reaction between NIH-HPG-UE and HCG varied from 34 to 87 % for the different antisera. One minimum estimate was 38%. An “LH-poor” NIHHPG- UE was able to neutralize only 18% of anti-HCG activity. Immunodiffusion in agar gel demonstrated a reaction of partial identity between HCG and LH. It was concluded that a partial immunologic cross-reaction between HPG and HCG exists and that LH is the component of HPG mainly responsible for the cross-reaction. (Endocrinology75: 352, 1964)