Office of NIH History Skip Navigation
top banner
Previous Page | Next Page  (3 of 12)
hCG Research at NIH/Page 2
hCG Research at NIH
Page 1
Page 2
Page 3
Page 4
Popular Culture
Your Stories
Further Reading

hCG Research at NIH

Human Chorionic Gonadotropin (hCG) was a fascinating hormone to study in 1970, partly because not much was known about its behavior or makeup. Scientists did know that the human body secretes hCG only during pregnancy or during certain kinds of cancers. If they could find a way to precisely measure the hormone, they would have a reliable tumor marker, as well as a way to identify problems with a pregnancy. NCI’s Roy Hertz was studying a cancer called choriocarcinoma at the time. In this disease, patients exhibited tumors that secreted hCG. The clinicians wanted a way to test blood samples reliably for the presence of hCG so that they could track the tumor during treatment.

JV: We knew that the bioassay that was used for monitoring the amount of hormone they were measuring was very crude, very insensitive, but it was better than anything else we had at that time. So we needed another way of measuring the hCG in the presence of a finite amount of LH [luteinizing hormone].

JV: While we were doing this, we had no idea of the impact on early pregnancy detection, abnormal pregnancy detection. In ectopic pregnancy, the levels of hCG usually start falling and they don’t rise as high as they do within a normal pregnancy.

However, measuring precise levels of hCG is exactly what the bioassays of the mid-twentieth century and the immunoassays of the 1960s could not do. The best test they had in 1970 was an immunoassay that could measure hCG but could not distinguish between hCG and luteinizing hormone (LH), another of the human gonadotropins that shares its biological characteristics.

GB: Griff and I spoke. “Wouldn’t it be great to develop a new assay for hCG.” At that time Judy Vaitukaitis was immunizing rabbits with subunits of hCG and harvesting antibodies.

Vaitukaitis was working at separating the subunits of hCG and determining their biological function and characteristics. In 1970 and 1971 she worked on generating an antibody that would be specific to the beta-subunit of hCG and that could therefore be used in a radioimmunoassay—so called because the process used radioactive labels in the immunoassay—and would not cross-react with other hormones in the body. In 1972, she found it. The first rabbit to produce the antibody was called “SB6” and became the baseline for future experiments.

JV: We were looking at structure-function studies of human chorionic gonadotropin. Was there biologic activity in the isolated subunit? What was it about the molecule that was responsible for the unique immunologic and biologic activity? Then we realized that the biologic effect of the hormone resided in the beta unit of hCG. So in doing these structure-function studies to understand where the immunologic and biologic specificity resided, it became obvious that you could really take advantage of the relative specificity of the antiserum.

JV: It was critical for [NICHD’s] John Robbins to be involved with this because he had the immunology background. Actually, we tried two doses of immunogen [to make the antibody], 10 and 50 micrograms, and so the animal that had the first dose of 50 micrograms of immunogen was labeled SB6, since it was the sixth rabbit. There were five rabbits immunized with 10 micrograms, and we were told they would never make antibody at 10. I said, “Let’s see.” We went down subsequently to 2 and showed it would respond at that, too. So the first animal that was immunized with 50 micrograms, SB6, became the classic antiserum that had the best relative specificity that was used for years, and we provided it all over the place.

back to top of page back to top
Griff Ross and Judith Vaitukaitis discuss their research, circa 1971
Griff Ross and Judith Vaitukaitis discuss their research, c. 1971.
Previous Page | Next Page  (3 of 12)
Office of NIH History | NIH | DHHS