scholarly journals Evaluation of Nicked Human Chorionic Gonadotropin Content in Clinical Specimens by a Specific Immunometric Assay

1999 ◽  
Vol 45 (1) ◽  
pp. 68-77 ◽  
Author(s):  
Galina Kovalevskaya ◽  
Steven Birken ◽  
Tatsu Kakuma ◽  
John Schlatterer ◽  
John F O’Connor
Keyword(s):  
Chorionic Gonadotropin ◽  
Human Chorionic Gonadotropin ◽  
Normal Pregnancy ◽  
Physical Separation ◽  
Vitro Fertilization ◽  
Clinical Specimens ◽  
Reference Preparation ◽  
Ectopic Pregnancies

Abstract We report the development and characterization of an IRMA for the direct measurement of nicked human chorionic gonadotropin (hCGn) in blood and urine. hCGn derived from a reference preparation of hCG used as an immunogen elicits monoclonal antibodies (mAbs) with enhanced recognition of human luteinizing hormone epitopes. The most specific assay for pregnancy hCGn is an IRMA composed of one mAb to choriocarcinoma-derived hCGn (C5) and a second mAb developed from immunization with normal-pregnancy hCGn. This assay was used to evaluate hCGn profiles in normal, in vitro fertilization, Down syndrome, and ectopic pregnancies. In all pregnancies, hCGn was usually present in much lower concentrations than the non-nicked hCG isoform. Our results suggest that some form of physical separation from the overwhelming quantities of non-nicked hCG present in clinical specimens will be required before accurate immunochemical estimations of hCGn can be made.

scholarly journals Early pregnancy human chorionic gonadotropin (hCG) isoforms measured by an immunometric assay for choriocarcinoma-like hCG

1999 ◽  
Vol 161 (1) ◽  
pp. 99-106 ◽  
Author(s):  
G Kovalevskaya ◽  
S Birken ◽  
T Kakuma ◽  
JF O'Connor
Keyword(s):  
Chorionic Gonadotropin ◽  
Early Pregnancy ◽  
Human Chorionic Gonadotropin ◽  
Normal Pregnancy ◽  
Clinical Samples ◽  
Molecular Heterogeneity ◽  
Vitro Fertilization ◽  
Binding Characteristics ◽  
Pregnancy Urine

Human chorionic gonadotropin (hCG) exhibits molecular heterogeneity in both its protein and carbohydrate moieties. This communication describes changes in hCG isoforms detected directly in clinical samples. These isoforms, quantified in blood or urine specimens, show a progression of change throughout normal pregnancy. Early pregnancy produces a type of hCG that resembles, in terms of immunoreactivity, a major form of hCG excreted in choriocarcinoma. The isoforms predominate for the first 5-6 weeks of gestation and then diminish, being replaced with the hCG isoforms which predominate throughout the remainder of pregnancy. The alteration in hCG isoform content occurs in both blood and urine. The progression of isoforms is best delineated by calculating the change in the ratio of the two forms, as many hCG assays either do not detect or fail to discriminate among these isoforms. An analogous pattern of hCG isoforms was observed in patients with in vitro fertilization pregnancies. hCG isolated from the pituitary displayed binding characteristics similar to those of the hCG derived from normal pregnancy urine. The early pregnancy hCG isoforms appear to have a differential expression in normal pregnancy as opposed to pregnancies which will not carry to term, suggesting that a determination of the relative balance of hCG isoforms may have diagnostic application in predicting pregnancy outcome.

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