Development of Specific Antisera for Human Chorionic Gonadotropin

  • Om P. Bahl
Part of the Biochemical Endocrinology book series (BIOEND)


A highly sensitive and specific radioimmunoassay (RIA) for human chorionic gonadotropin (hCG) not only is of considerable value in the detection of normal (Goldstein et al.,1968; Varma et al.,1971; Vaitukaitis et al.,1972) and ectopic pregnancies (Braunstein et al., 1978; Franchi-mont et al.,1978; Kosasa et al.,1973; Rasor and Braunstein, 1977; Milwidsky et al., 1978) but also is important in the diagnosis and management of hCG-producing neoplasms (Rutanen and Seppälä, 1978; Vaitukaitis, 1979; Ross, 1977; Jones et al., 1975). Therefore, there have been continued efforts made toward the refinement of RIA for hCG by enhancing its sensitivity and specificity. Several basic advances including the purification and structural elucidation of various glycoprotein hormones and the techniques for radioisoptic labeling of proteins have contributed a great deal to the development of various assays for hCG. As the purified hCG (Bahl, 1969, 1973) became available, several assays based on the use of [125I]-hCG and anti-hCG were developed. While these assays served a useful purpose, they suffer from the limitation of cross-reactivity with other gonadotropins, in particular with human luteinizing hormone (hLH). The next breakthrough came when hCG was first dissociated into subunits and the subunits were separated (Swami-nathan and Bahl, 1970; Bahl, 1977; Morgan and Canfield, 1971). As a result, the structural elucidation of the subunits was accomplished (Bellisario et al., 1973; Carlsen et al., 1973; Kessler et al., 1979a,b; Morgan et al.,1975). It was recognized that whereas the a-subunits of all glycoprotein hormones were nearly identical (Bellisario et al,1973), the α-subunits had significant differences (Carlsen et al, 1973; Giudice and Pierce, 1978). Also, the β-subunit of hCG (hCG-/3) was found to have a unique feature of having at the carboxy terminus an additional 30-residue fragment that was missing from other hormones. This resulted in the use of anti-hCG-0 or anti-carboxy terminal peptide antisera in place of anti-hCG antiserum in the RIA for hCG. Although anti-hCG-β antiserum has the ability to discriminate between hCG and hLH, it has some cross-reactivity with the latter. Nevertheless, the assays based on antihCG-β are relatively more specific than those involving anti-hCG. On the other hand, the assays employing anti-carboxy terminal peptide are highly specific but lack sensitivity due to poor affinity of the antibody for hCG. Thus, it is clear that while anti-hCG-0 lacks specificity, the anticarboxy terminus lacks sensitivity. We have therefore attempted to modify hCG-0 so as to obtain a specific antigen and thereby a specific antibody for hCG RIA. This chapter describes the structure and function studies of hCG-β related to the development of the hCG-specific antigen. The properties of the antibody and its application to a specific RIA for hCG are also discussed.


Disulfide Bond Ectopic Pregnancy Human Chorionic Gonadotropin Carboxy Terminus Specific Antiserum 


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Copyright information

© Plenum Press, New York 1981

Authors and Affiliations

  • Om P. Bahl
    • 1
  1. 1.Department of Biological Sciences, Division of Cell and Molecular BiologyState University of New York at BuffaloBuffaloUSA

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