Toshitaka Ogawa

Characteristic Differences in Immunohistochemical Localization of New Placental Proteins (PP1, PP19, PP21) in the Human Placenta

The immunohistochemical localization in the human placenta of new placental proteins PP1, PP19, and PP21 was clarified using modified indirect enzyme-labeled antibody method and compared with that of pregnancy-specific beta 1-glycoprotein (SP1). The major results are as follows: positive staining for PP1 was seen at the nucleus and cytoplasm of villous cytotrophoblasts, the X cells at the basal plate, and of chorionic trophoblasts, while the decidua cells and amnion were not stained. PP19 was characteristically seen in the nucleus and cytoplasm of syncytiotrophoblasts. X cells in basal plate, chorionic trophoblasts, and maternal leukocytes. The villous cytotrophoblasts, decidua cells, and amnion were not stained. PP21 localization was found at the microvilli and basal membrane of syncytiotrophoblasts and at the cytotrophoblast plasma membrane of the chorionic villus in early gestation. In late gestation, increased staining was seen at the syncytiotrophoblast microvilli and the villous basement membrane, and moderate staining at plasma membrane of the amniotic epithelium and chorionic trophoblasts. SP1 was found only at the syncytiotrophoblast cytoplasm of chorionic villi. Studies using these four placental proteins simultaneously may therefore provide a new key learning about unknown metabolic functions of trophoblasts.

Diagnostic Reliability of Simultaneous Measurements of Beta Human Chorionic Gonadotropin and Pregnancy-Specific Beta-1-Glycoprotein in Serum of Patients with Trophoblastic Disease

Serum levels for beta-human chorionic gonadotropin (beta-hCG) and pregnancy-specific beta 1-glycoprotein (SP1) in patients with trophoblastic disease were measured by radioimmunoassay and enzyme-linked immunosorbent assay. The beta-hCG:SP1 ratios were below 1.0 in all 22 cases of complete hydatidiform mole and in 8 of 9 cases of partial hydatidiform mole. Two (10.5%) of 19 cases of invasive mole involving metastasis had ratios that rose above 1.0 during chemotherapy. Ratios ranged from 1.6 to 29 in 11 of 15 cases of choriocarcinoma before chemotherapy. The remaining 4 cases, diagnosed within 3 months of antecedent pregnancy, had ratios below 0.99. Thus, the difference between choriocarcinoma and nonchoriocarcinoma beta-hCG:SP1 ratios may be due to trophoblastic differentiation based on the developmental stage and with trophoblast age, or due to the mass and potential activity of trophoblastic cells.

Placental Protein 21

The immunohistochemical localization of placental protein 21 (PP21) was marked in the syncytial brush border and basal membrane during the 1 st and 2nd trimesters of pregnancy and also in the chorionic epithelial brush border and basement membrane at term. A weaker stain was found in the cell membranes of amniotic epithelial and chorionic trophoblast cells. Neither heparin nor changes in temperature significantly influenced PP21 concentration. Relatively high serum PP21 concentrations were measured during the follicular and luteal phases in healthy nonpregnant women and in healthy men whose seminal plasma also showed a high PP21 concentration. Serum PP21 levels in normal pregnancy rose from a median of 29.1 ng/ml at 6–7 weeks of gestation to 82.0 ng/ml at 36–37 weeks of gestation. Although maternal urine showed low PP21 levels during pregnancy, amniotic fluid PP21 levels were higher at 7–21 weeks of gestation than at term. Cord blood sera showed almost the same PP21 concentration as maternal sera, but retroplacental blood showed much higher levels. Maternal serum PP21 levels in hydatidiform mole patients did not differ from the normal pregnancy range, although their molar vesicular fluids contained higher PP21 concentrations. These results suggest an extraplacental source for PP21.

Serum Concentration of Placental Proteins (PP5 and PP10) in Toxemia of Pregnancy as Related to Intrauterine Growth Retardation

Maternal serum concentrations of placental proteins 5 (PP5) and 10 (PP10) were measured by radioimmunoassay in 568 samples obtained from 308 healthy pregnant women and 63 women having toxemia of pregnancy. Below-normal PP5 values were more widely distributed in the mild than in the severe toxemia group, while the incidence of above-normal PP5 values was found only in the severe toxemia group. The incidence of below-normal PP10 values was higher in the severe than in the mild toxemia group. Our study thus suggests that simultaneous measurement of PP5 and PP10 concentrations in maternal serum in toxemia of pregnancy is a useful monitoring technique for predicting progressive pathological change and placental dysfunction related to IUGR.

Circulating Levels of Placental Protein 5 in Normal and Abnormal Pregnancies

Serum concentrations of PP5 were measured by radioimmunoassay in 219 women with normal pregnancies and 163 women whose pregnancies were complicated. PP5 in serum disappeared rapidly after delivery, with a half-life of 5-10 min in the first 10 min. Serum PP5 levels were higher in uterine than in antecubital venous blood. In normal pregnancies, PP5 was detectable at 7-8 weeks of gestation; its mean concentration rose gradually to a maximum of 17.8 +/- 10.2 ng/ml at 34-35 weeks of gestation. Elevated serum PP5 concentrations were noted in patients whose pregnancies were complicated by toxemia of pregnancy with appropriate-for-date baby or by twin pregnancy. Low serum PP5 concentrations tended to be found in patients whose pregnancies were complicated by abortion, intrauterine fetal death, and hydatidiform mole. Marked abnormal PP5 levels were not found in patients with maternal diabetes and placenta previa. These findings suggest that the assay of serum PP5 concentrations can be a useful parameter in determining the prognosis of abnormal pregnancies.

Studies on α2-plasmin inhibitor and UK inhibitor in pregnancy and labor

To find out whether the depressed fibrinolytic activity in pregnancy can be ascribed to an increased content of inhibitors in the blood or to a release of inhibitors from the placenta, we studied the variation of the fibrinolytic inhibitors such as α1-AT, α2-MG, AT-III and C1-inactivator during pregnancy. However, we did not find any significant increase in inhibitors. In this paper, the levels of antiplasmin including α2-PI devised by Aoki and UK inhibitors extracted from the placenta by Kawano during pregnancy and delivery were examined.Methods:The material consisted of citrated plasma from pregnant women and extracts from the placenta. α2-PI was assessed with a single radial immunodiffusion method using antiserum made by Aoki. Antiplasmin activity was measured with chromogenic substrate S-2251 and then UK inhibitor was calculated from a standard curve prepared from placental UKI using the chromogenic substrate S-2444. The results were expressed relative to the content of normal standard as %, iu/ml and u/g.Results:1) The levels of α2-PI with a single radial immunodiffusion method correlated well to those of antiplasmin using the chromogenic substrate S-2251.2) Antiplasmin activity including α2-PI remained unchanged throughout pregnancy within 80-130%, and followed a similar patern after delivery. How-ever, it relatively decreased in retroplacental blood as well as uterine venous blood.3) In extracts of the placenta the concentration of antiplasmin was low.4) On the other hand, extract of the placenta contained a high concentration of UKI.5) The concentration of UKI was extremely low in each trimester, but the increased values were noted at term and in labor as well as in retroplacental blood, and gradually decreased after delivery.Discussion: Antiplasmin activity might directly or indirectly act upon the depression of the fibrinolytic activity in pregnancy, but UK inhibitor might be found intensively during placental separation.