Immunohistochemical study of tissue polypeptide antigen (TPA) and cancer antigen 125 (CA125) in the human and cynomolgus monkey placenta, umbilical cord and decidua

Distribution of CA 125 in Placental Tissues

The presence of the tumor marker CA 125 was studied in different compartments of the human placenta. Levels of CA 125 in the cytosol of chorionic villi ranged from 27 - 17100 U/g (median 560 U/g). In the placental amnion and chorion concentrations ranged from 175-29000 U/g, median 1060 U/g and were not statistically different. In the umbilical cord values were significantly lower (range 44 - 7600 U/g; median 180 U/g).

Maternal serum probes were above the upper limit of normal in all cases (range 48 - 500 U/ml; median 131 U/ml). Immunohistochemistry detected CA 125 exclusively within the amniotic cells of the placenta and the umbilical cord. This might be because CA 125 fixes more to insoluble structures in the amnion or because of contamination of chorionic villi with the underlying decidua.

Monoclonal antibody DS6 detects a tumor-associated sialoglycotope expressed on human serous ovarian carcinomas

A newly developed murine monoclonal antibody, DS6, immunohistochemically reacts with an antigen, CA6, that is expressed by human serous ovarian carcinomas but not by normal ovarian surface epithelium or mesothelium. CA6 has a limited distribution in normal adult tissues and is most characteristically detected in fallopian tube epithelium, inner urothelium and type 2 pneumocytes. Pre-treatment of tissue sections with either periodic acid or neuraminidase from Vibrio cholerae abolishes immunoreactivity with DS6, indicating that CA6 is a neuraminidase-sensitive and periodic acid-sensitive sialic acid glycoconjugate ("sialoglycotope"). SDS-PAGE of OVCAR5 cell lysates has revealed that the CA6 epitope is expressed on an 80 kDa non-disulfide-linked glycoprotein containing N-linked oligosaccharides. Two-dimensional non-equilibrium pH gradient gel electrophoresis indicates an isoelectric point of approximately 6.2 to 6.5. Comparison of the immunohistochemical distribution of CA6 in human serous ovarian adenocarcinomas has revealed similarities to that of CA125; however, distinct differences and some complementarity of antigen expression were revealed by double-label, 2-color immunohistochemical studies. The DS6-detected CA6 antigen appears to be distinct from other well-characterized tumor-associated antigens, including MUC1, CA125 and the histo-blood group-related antigens sLea, sLex and sTn.

Immunoradiometrical measurement of tissue polypeptide specific antigen (TPS) in normal, healthy, nonpregnant and pregnant Japanese women

Using a monoclonal immunoradiometrical assay, we measured the concentrations of the specific epitope M3 of tissue polypeptide antigen (TPA), namely, tissue polypeptide specific antigen (TPS), in serum and amniotic fluid obtained from normal, healthy, nonpregnant and pregnant Japanese women (NHNJW and NHPJW). The cut-off value of the serum TPS level was set at 130 U/l, based on the mean +2 standard deviations in the NHNJW. The serial measurement of serum TPS levels demonstrated the significant temporal elevation of TPS level near the time of ovulation (+/- 3 days) in the ovulatory women. In the NHPJW, the mean serum TPS level and the positivity rate (> 130 U/l) increased with the advance of gestation, reaching 183.7 U/l and 66.7%, respectively, in the third trimester. Maternal serum levels were much elevated just before (mean: 982.3 U/l) and after (mean: 824.6 U/l) delivery, and were reduced to about one-fourth by 3 days. In addition, markedly high TPS concentrations were found in the retroplacental blood (one case: 9,076 U/l) and the amniotic fluid (mean: 11,650 U/l). The serum TPS level correlated well (r = 0.871) with the serum TPA level in the TPS range of 2-2,000 U/l, while a poor correlation (r = 0.273) was found in the TPS range of 2-500 U/l. The present study thus obtained fundamental data on TPS in Japanese women. The fluctuation and change of serum TPS levels during the menstrual cycle and in pregnancy should be taken into consideration when we apply TPS as a tumor marker for women.

The development of an enzyme immunoassay for placental tissue protein 17 (PP17) and its clinical significance

We developed an enzyme immunoassay (EIA) for placental protein 17 (PP17) using avidin biotin binding, and measured the serum-PP17 levels of 37 healthy men, 103 nonpregnant women, 48 pregnant women, and 86 patients with gynecologic malignancies. The mean level was 12.8 ng/ml in healthy men and 44.2 ng/ml in nonpregnant women (p < 0.05). The calculated upper limit of normal was 97.8 ng/ml (mean + 2 sigma). The serum PP17 concentration was remarkedly reduced postmenopausally. Pregnant women showed a mean serum level of 19.2 ng/ml, which was significantly lower than that of nonpregnant women. Immunoserological results strongly suggest that PP17 is produced far more in the normal endometrium than in the placentae and decidua. Patients with gynecologic malignancies had obviously lower mean serum PP17 levels (8.3-19.9 ng/ml) than those found in healthy nonpregnant women. Measurement of the serum PP17 concentration might be useful in distinguishing gynecologic malignancies from various normal conditions.

Immunohistochemical and immunoelectron microscopic study of cytochrome P-450 of human fetal livers (P-450HFLa): implications for an onco-feto-placental enzyme

Cytochrome P-450 of human fetal livers (P-450HFLa) was demonstrated by the avidin-biotin immunoperoxidase technique in tissue samples as follows: human fetal organs, adult livers, human and cynomolgus placenta, and gynecologic organs which were obtained from 40 patients with gynecologic malignancies and 32 patients with benign diseases. P-450HFLa was clearly localized in the cytoplasm and membranes of the hepatocytes, and the fact was confirmed by an immunoelectron microscopic examination. In addition, a semiquantitative assay of staining intensity demonstrated that this enzyme tended to decrease with advancing age. These findings suggest that hepatic P-450HFLa synthesis is inversely proportional to age, and that this enzyme is one of the differentiation antigens. P-450HFLa was also detected immunohistochemically in other fetal organs. The present study thus confirms that P-450HFLa is not specific to the liver and is ubiquitous even in the fetus. Marked positive staining for P-450HFLa was demonstrated in villous syncytiotrophoblasts. In contrast, no positive staining was found in the cynomolgus-monkey placenta, unlike the case for many other placental antigens. These findings lead to the tentative conclusion that P-450HFLa is a feto-placental enzyme peculiar to humans. P-450HFLa was demonstrated to occur very frequently in gynecologic malignancies. The mean positivity rate for all gynecologic malignancies was 85%, while the rate was below 25% for benign gynecologic diseases, indicating that P-450HFLa is one of the onco-feto-placental enzymes. The present study thus suggests that this enzyme could be a promising new tumor marker for gynecologic malignancies.

What do we know about the origin of CA 125?

The murine monoclonal antibody OC 125 recognizes an epitope on a molecule called Cancer Antigen 125 (CA 125). The CA 125 antigen is expressed in amnion and its derivatives of fetal coelomic epithelia (such as Müllerian epithelia, peritoneum, pleura and pericardium) and in many adult tissues (such as the epithelium of fallopian tubes, endometrium, endocervix, pleura and peritoneum). The normal endometrium produces CA 125 and this production can contribute significantly to the level of circulating CA 125 at the time of menstruation. During peritoneal irritation (hyperstimulation, salpingitis, ruptured ectopic pregnancy, laparotomy) peritoneally derived CA 125 significantly contributes to circulating CA 125 concentrations, giving elevated CA 125 values. The use of the CA 125 serum assay as a single diagnostic tool is restricted by the fact that the antigen CA 125 is produced by normal epithelia (of peritoneum, endometrium and benign ovarian cysts) and not only by the ovarian cancer cell.

Occurrence of the mucinous differentiation antigen CA125 in genital tract and conductive airway epithelia of diverse mammalian species (rabbit, dog, monkey)

CA125 is a human tumor-associated antigen of coelomic epithelial origin. In the present study, immunohistochemical analysis of normal rabbit, dog, and monkey tissues using monoclonal antibody OC125, revealed that in these animals positive staining for CA125 is found in all tissues that produce this mucin-like glycoprotein in man, i.e., the peritoneal and pleural mesothelium, the different Müllerian-duct-derived epithelia of the female genital tract, and the epithelium of trachea, bronchi, bronchioli, and mucoserous respiratory glands; CA125 was also detected in some ductal and acinar cells of the dog mammary gland. Without trypsin treatment of sections, staining was predominantly localized on the apical cell surface of all mentioned cell types. After treatment, mucin droplets inside respiratory mucous cells were also positively stained. In all cases, staining was associated with material positive for periodic acid-Schiff (PAS) and Alcian blue. In rats, its presence could not be demonstrated. Our results show that the CA125 epitope is not restricted to man and that its expression throughout different animal species is associated with well-defined tissue compartments. The expression of the mucous differentiation antigen CA125 in several common laboratory animals provides new opportunities for the experimental study of its biological significance.

Immunoradiometrical measurement of tissue polypeptide antigen (TPA) and cancer antigen 125 (CA125) in pregnancy and at delivery

Using conventional radioimmunoassay kits, we measured concentrations of two cancer-related antigens, tissue polypeptide antigen (TPA) and cancer antigen 125 (CA125) throughout gestation and at delivery. The maternal serum was collected from 147 pregnant women between 5 and 43 weeks gestation and 27 women were studied at delivery at which time samples of maternal blood, umbilical artery and vein blood as well as amniotic fluid were collected. The various concentrations of TPA and CA125 were compared with placental weight and infant birth weight. The results are summarized as follows: (1) Mean TPA levels in maternal serum increased with advancing gestation and rose above 110 U/l (upper non-pregnant limit) from 35 weeks onwards. Mean CA125 levels rose above 35 U/ml (normal non-pregnant upper limit) before 9 weeks gestation and thereafter fell. Both levels were markedly raised immediately after delivery. (2) In umbilical artery and vein serum, mean TPA levels were slightly raised. However, there were no significant differences between TPA levels in maternal serum and matched serum from the umbilical artery and vein. Mean umbilical CA125 levels were below 35 U/ml, while mean CA125 levels were significantly higher in the corresponding maternal serum. (3) The concentrations of TPA and CA125 were extremely high in amniotic fluid. The mean values reached 3604 U/l and 2187 U/ml, respectively. (4) None of the concentrations of TPA and CA125 in those pregnancy-related body fluids correlated significantly with birth weight, placental weight or fetal sex. These findings suggest that the production of these two cancer-related antigens is not by the fetus but the placenta.