Measurement of pregnancy-associated plasma proteins during human gestation

Pregnancy-associated plasma protein A: a clinically significant predictor of early recurrence in stage II breast carcinoma

The primary tumors and metastases from 30 patients with stage II breast carcinoma treated with low- or standard-dose combination chemotherapy (cyclophosphamide, methotrexate, 5-fluorouracil) were studied by the immunoperoxidase technique for pregnancy-associated plasma protein A (PAPP-A), pregnancy-specific beta-1-glycoprotein (SP-1), and placental protein five (PP-5). In addition to immunostaining, 25 traditional clinicopathologic features were assessed with respect to early (at less than two years) recurrence. Of the 11 patients with early recurrences, nine (82 per cent) were PAPP-A-positive, while 16 of the 19 patients without early recurrences (84 per cent) were PAPP-A-negative (P less than 0.0005). None of the other clinicopathologic features correlated with early recurrence. Immunostaining for PAPP-A is thus a clinically significant predictor of early recurrence in patients with stage II breast carcinoma.

Intermediate trophoblast: a distinctive form of trophoblast with specific morphological, biochemical and functional features

Morphological and immunohistochemical analysis of placental tissue from 12 days to term using antibodies directed against the unique carboxyl terminal peptide of human chorionic gonadotrophin beta subunit, human placental lactogen (hPL) and pregnancy-specific beta I-glycoprotein reveals that an intermediate form of trophoblast with distinctive features exists. This cell has a diverse morphological expression and is located overlying chorionic villi, in the trophoblastic columns, basal plate and the trophoblastic shell. Although all three placental proteins are localized in this cell the predominant hormone is hPL, which can serve as an immunocytochemical marker. One of the primary functions of this cell is in implantation and in the establishment of the uteroplacental circulation since it extensively invades the spiral arteries at the placental site. It is proposed that this distinctive form of trophoblast be termed 'intermediate trophoblast'.

Immunohistochemical localization of pregnancy-associated plasma protein A (PAPP-A) in placentae from normal and pre-eclamptic pregnancies

An immunohistochemical method was used to locate pregnancy-associated plasma protein A (PAPP-A) in the placenta and uterus. In addition to 10 placentae and basal plates from normal pregnancies, ranging in gestational age from 37 to 40 weeks, the following specimens were studied: three uteri obtained by hysterectomy during early pregnancy; and three placentae from patients with severe hypertensive pre-eclampsia. In early gestation, PAPP-A was localized in the villous cytotrophoblastic cell layer and the endometrial glands but was not found in the villous syncytiotrophoblast, the cytotrophoblastic cell columns or the decidual cells. On histochemical examination of placentae from cases of pre-eclampsia with hypertension, an increased number of villous cytotrophoblastic cells and so-called X-cells was observed. The monospecific antiserum to PAPP-A reacted strongly and evenly with the cytoplasm of these cells. The present study strongly suggests that the active production sites of PAPP-A are the villous cytotrophoblastic cells and the X-cells.

In vitro production of pregnancy-associated plasma protein A by human decidua and trophoblast

Immunohistochemical techniques and direct measurements of pregnancy-associated plasma protein A (PAPP-A) have demonstrated the presence of PAPP-A in trophoblast and decidua. The purpose of the present study was to investigate the possibility that these tissues are capable of producing PAPP-A in vitro. Trophoblast and decidua were obtained from term deliveries and from legal surgical terminations of pregnancy (7 to 12 weeks). In addition to trophoblast and decidua, myometrium was also obtained during two hysterectomies in the first trimester of pregnancy. Tissues were incubated in medium 199 at 37 degrees C under an oxygen/carbon dioxide atmosphere. Media containing either pregnancy-associated serum or non-pregnancy-associated serum were changed after 8 hours of incubation in medium 199 alone. In addition to PAPP-A, human placental lactogen (hPL) and prolactin (Prl) were measured in homogenates and media by radioimmunoassays in order to confirm the viability of the cultured tissues. Addition of pregnancy-associated serum to the media induced a significant release of PAPP-A from trophoblast and decidua when compared to that in control cultures. Non-pregnancy-associated serum had no effect. Myometrium did not release any measurable PAPP-A into the medium even in the presence of pregnancy-associated serum. Cycloheximide added to pregnancy-associated serum significantly inhibited the release of PAPP-A from trophoblast and decidua. These last tissues, irrespective of the culture condition, released significantly more PAPP-A as well as hPL and Prl than was initially present in the tissue. These data demonstrate that PAPP-A is released in vitro by trophoblast and decidua (but not by myometrium) and that this release can be magnified by a factor present only in pregnancy-associated serum. The release of PAPP-A, hPL, and Prl is considered as a de novo production since concentration of these proteins are higher in media and tissues after incubation compared to concentrations initially present in the tissue before culture and since cycloheximide significantly inhibits the release of PAPP-A, Prl, and hPL from the cultured tissues.

Pregnancy-associated plasma protein A (PAPP-A) specifically inhibits the third component of human complement (C3)

Pregnancy-associated plasma protein A (PAPP-A), a macromolecular glycoprotein associated with pregnancy, was shown to inhibit complement-induced haemolysis and to bind heparin reversibly. Because of the inhibitory effects of heparin on the complement cascade it was not clear if the inhibition of complement activity observed with PAPP-A (isolated from heparin plasma) was attributable to the heparin moiety bound to PAPP-A. This work demonstrates that heparin exerts an inhibitory effect on complement activity but that heparin-free PAPP-A is also inhibitory. PAPP-A specifically inhibits C3 by binding to this complement subcomponent and not by inhibiting C3 convertase as demonstrated for C3 inactivator.

Circulating levels of pregnancy-associated plasma protein-A (PAPP-A) and human chorionic gonadotrophin (hCG) in intrauterine and extrauterine pregnancies

Pregnancy-associated plasma protein-A (PAPP-A) and human chorionic gonadotrophin (hCG) have been measured in the plasma of pregnant and non-pregnant women attending the outpatient clinic for suspicion of pregnancy. The plasma concentrations obtained were grouped into intrauterine or extrauterine pregnancies and compared with values obtained in non-pregnant patients with similar periods of amenorrhoea. Patients with ectopic pregnancies had slightly lower PAPP-A levels and significantly lower hCG concentrations than those in women with normal intrauterine pregnancies. Non-pregnant women had very low hCG and PAPP-A levels compared with those in pregnant patients. These data suggest that in patients with extrauterine pregnancies the poorly sustained ectopic trophoblast is unable to produce normal concentrations of hCG and probably PAPP-A and that the slightly diminished levels of PAPP-A in ectopic pregnancies might be derived from a decidual production.

Tissue and plasma concentrations of pregnancy-associated plasma protein-A (PAPP-A): comparison with other fetoplacental products

Human placental lactogen (hPL), alpha fetoprotein (AFP), prolactin (PRL) and pregnancy-associated plasma protein-A (PAPP-A) were measured by radioimmunoassay in plasma, in homogenates of trophoblast, decidua, chorion, amnion and in amniotic fluid from 10 patients after non-complicated term delivery. Plasma samples and homogenates of trophoblast and decidua were also collected from 10 patients undergoing surgical termination of pregnancy between 7 and 12 weeks gestation. In addition, plasma and endometrial samples from 10 patients undergoing hysterectomy for other indications than malignancy were analysed for comparison. The highest tissue concentrations of hPL, AFP and PRL corresponded in each case to the known site of synthesis. For PAPP-A the highest concentration was found in maternal plasma at term [238.8 +/- 75.6 (SEM) micrograms/ml]. The highest tissue concentration was found at term in the decidua (57.0 +/- 2.0 micrograms/g), more than three times higher than that in the trophoblast (16.9 +/- 5.4 micrograms/g). The concentrations of PAPP-A in endometrial samples from non-pregnant women (1.9 +/- 0.6 micrograms/g) was 40 times higher than that in the corresponding plasma samples (0.05 +/- 0.02 microgram/ml). These observations point to the decidua as a possible source of PAPP-A.

Amniotic fluid and plasma concentrations of pregnancy-associated plasma protein-A (PAPP-A) throughout pregnancy: comparison with other fetoplacental products

The development of a sensitive radioimmunoassay has enabled measurements of pregnancy-associated plasma protein-A (PAPP-A) to be performed from early pregnancy. The present paper compares the plasma concentrations of PAPP-A with the levels of two trophoblastic proteins, human placental lactogen (hPL) and the beta-subunit of human chorionic gonadotrophin (beta-hCG), with a steroid of fetoplacental origin, total oestriol (total E3), and with a fetal protein, alpha-fetoprotein (AFP). PAPP-A was also measured in amniotic fluid and in maternal urine. In contrast with the secretion of the other substances studied, which either reach a plateau or even decrease during the last 4 weeks of pregnancy, PAPP-A steadily increased in the maternal circulation from 7 to 40 weeks gestation. It is proposed that PAPP-A production is either not related to placental mass or that PAPP-A is not of trophoblastic origin. The increase of PAPP-A in amniotic fluids parallels the increase in maternal blood; virtually no PAPP-A is excreted in urine.

Concentrations of placental proteins (HPL and SP1) in maternal serum throughout normal pregnancy

Throughout 65 normal singleton pregnancies 332 blood samples were obtained and analyzed for pregnancy-specific beta 1 glycoprotein (SP1) and human placental lactogen (HPL). The measurement of SP1 in maternal serum was made using radial immunodiffusion, that of HPL by using radioimmunoassay. There was wide variation in the number and timing of blood samples obtained from patients, and therefore the results could not be used to construct a regression curve by the usual methods applied to independent measurements. Consequently only one value per patient was chosen at random as a basis for calculations. A second degree polynomial for the logarithm of the serum concentrations yielded an optimal fit for both parameters. Tolerance intervals of 90% were calculated for use in future studies.

Pregnancy-associated plasma protein-A (PAPP-A) and hCG in early pregnancy

Pregnancy-associated plasma protein-A (PAPP-A) is a recently described glycoprotein of unknown biological function. The development of a radioimmunoassay enabled us to measure plasma levels of PAPP-A and human chorionic gonadotrophin (hCG) in 12 non-pregnant volunteers and in 159 women in early pregnancy attending the outpatient clinic for legal abortion. PAPP-A but not hCG was measurable in all non-pregnant women. In pregnant patients (with 36 to 86 days of amenorrhea) hCG reached a peak value (163.1-197.6 ng/ml) between the 9th and the 13th week whereas PAPP-A steadily increased throughout this period of pregnancy. Between the 6th and the 13th week after the last menstrual period, levels of PAPP-A increased proportionally more than hCG. This work provides the first evidence of a PAPP-A production in non-pregnant subjects and the very early marked increase of PAPP-A secretion during pregnancy.

Heterogeneity of pregnancy-specific beta 1-glycoprotein following purification from maternal serum and partial characterization of a high-molecular-weight component

Pregnancy-Specific beta 1-Glycoprotein (PSB1G) has been purified from maternal serum by physico-chemical and immunochemical methods. Marked instability of the protein was noted after partial purification which correlated with hydroxylapatite chromatography of PSB1G. Three molecular heterogeneous forms were demonstrated by gel filtration on Sephacryl S-200 which were designated as PSB1G-I, II and III. Each of the latter purified materials displayed altered immunoelectrophoretic mobility, i.e., altered from beta 1 to gamma mobility. In immunodiffusion experiments PSB1G-I reacted in complete immunological identity with 'native' serum PSB1G whereas PSB1G-II and III reacted in partial identity with each of the latter, suggesting that they are dissociation and/or degradation products of the parent PSB1G. The apparent molecular weights of PSB1G-I, II and III as determined by gel filtration were 280 000, 69 000 and 23 000, respectively, PSB1G-I was selected for structural analysis on the basis of its immunological identity with 'native' antigen. SDS-PAGE studies of PSB1G-I with and without reducing agent strongly suggest that PSB1G-I and 'native' serum antigen are composed of two dissimilar subunits of equal molecular size which are bonded together by non-covalent linkage. One of the subunits appears to represent a single polypeptide chain, whereas the other subunit appears to be composed of two polypeptide chains of unequal size that are linked together by covalent bonds. Investigations are continuing towards confirmation of the proposed structural model of PSB1G-I by an alternate methodology of protein structure analysis.

Sequential fluoroimmunoassay for measurement of pregnancy specific beta 1 glycoprotein using antibody coupled to magnetisable particles

A direct, sequential fluoroimmunoassay has been developed for the determination of serum levels of pregnancy specific beta 1 glycoprotein (SP1). The method employs rabbit anti-SP1 serum coupled to magnetisable cellulose-iron oxide particles and fluorescein-labelled SP1. Serum samples or standards are incubated with magnetisable solid phase anti-SP1 for 30 min. After magnetic sedimentation of the particles, the supernate, which includes endogenous fluorophores and other interfering factors, is discarded. Fluorescein-labelled SP1 is then added and incubated for a further 45 min; the particles are again sedimented and the fluorescence of the labelled SP1 remaining in the supernate is estimated. This reading related directly to the SP1 content of the original sample. The entire procedure, including fluorometry, is performed within a single disposable polystyrene test tube and is sufficiently simple and reliable for routine application. The sensitivity, specificity and precision is very similar to that of radioimmunoassay, and the results correlate with those of the radioimmunoassay (r = 0.9887).

Pregnancy-associated plasma protein A: circulating levels during normal pregnancy

The development of specific and sensitive electroimmunoassays for a recently identified high molecular weight alpha-2 mobile pregnancy-specific protein (pregnancy-associated plasma protein A, PAPP-A or SP4) is described. These assays have permitted the detection of circulating levels of PAPP-A (10 microgram/L) as early as the fifth week of pregnancy. In all 18 subjects studied, the levels of PAPP-A rose from first detection in the first trimester until delivery at term. The development of these assays now permit the evaluation of PAPP-A measurement as a diagnostic test of early pregnancy and as an index of fetal well-being throughout gestation.

The relationship between changing values of pregnancy-associated plasma protein-A in late pregnancy and the onset of labour

The pattern of change of PAPP-A was established in three separate groups of patients. Day-to-day change from the 38th week was measured in six healthy patients whose pregnancies ended in spontaneous labour. The slow fluctuations of PAPP-A suggest that values found in labour are a consequence of events prior to the onset of labour. Increases of PAPP-A during the last few days of pregnancy and into labour were compared in patients going into labour spontaneously and patients who were induced. The induced patients showed a sharper increase in PAPP-A during this interval than the spontaneous onset group. A comparison at an earlier stage of pregnancy of PAPP-A increase was made between normal pregnancies going into labour on or before 280 days and those who went into labour later. Between 31 +/- 1 and 35 +/- 1 weeks, those who delivered in the earlier group showed a sharper rise in PAPP-A. It seems likely that the behaviour of PAPP-A in late pregnancy is the consequence of uterine activity and it seems unlikely that an increasing level of PAPP-A in itself has anything to do with the initiation of spontaneous labour.

Purification of pregnancy-associated plasma protein-A by a two step affinity chromatographic procedure

A high molecular weight pregnancy specific protein (PAPP-A) was purified by immunospecific affinity chromatography. The purification procedure was based on a new method for affinity chromatography using direct coupling of precipitable immune complexes to the gel matrix. The procedure was performed in two steps: a positive immunospecific affinity chromatography followed by a negative affinity chromatography in which balanced amounts of anti-contaminant antibodies were used as ligant. The purified material at a concentration of 300 microgram/ml was tested by immunoelectrophoretic methods and no contaminants were detectable. WHO beta-1 SP1 reference material 78610 contained 45 microgram PAPP-A/ml.

Pregnancy-associated plasma protein-A: an inhibitor of the complement system

Pregnancy-associated plasma protein-A (PAPP-A) was purified to homogenicity from third-trimester pregnancy plasma using ion exchange chromatography and affinity chromatography on con A-Sepharose and anti-human serum-Sepharose. The elution of PAPP-A, alpha 2-macroglobulin, Cl-inhibitor and alpha 1-antitrypsin was followed by immuno-diffusion. the eluates were tested for stimulation or inhibition of complement-induced haemolysis. PAPP-A markedly inhibits the haemolytic activity of complement.

Interrelationships of human chorionic gonadotropin, human placental lactogen, and pregnancy-specific beta 1-glycoprotein throughout normal human gestation

Human chorionic gonadotropin (hCG), human placental lactogen (hPL), and pregnancy-specific beta 1-glycoprotein (PSBG) were measured by radioimmunoassay in 270 samples of serum from women with uncomplicated pregnancies. All three proteins were significantly correlated with each other in individual samples of serum and with the estimated trophoblastic mass during the first trimester. No significant correlation could be demonstrated between the concentrations of hCG and PSBG in maternal serum during the second or third trimesters or between the concentrations of hCG and hPL during the second trimester. Levels of PSBG and hPL in serum were significantly correlated throughout all three trimesters. These findings suggest that the secretion of hCG, hPL, and PSBG may be regulated by similar control mechanisms during the first trimester of pregnancy. However, after this period, the factors that modulate the production of hCG differ from those that regulate the production of hPL and PSBG.

Relationship of obstetric parameters to the concentration of pregnancy-associated plasma protein A

Pregnancy-associated plasma protein A (PAPP-A) was measured by rocket immunoelectrophoresis in 272 patients at 34 weeks of pregnancy and within 48 hours before delivery. The values obtained have been compared to maternal parameters (age, weight, weight gain, blood group, rhesus factor, and parity) and to fetal parameters (sex, weight, Apgar score, rhesus factor, blood group, and placental weight). Maternal age, increased parity, and increased body weight are related to decreased PAPP-A levels. On the other hand, mothers carrying male fetuses, rhesus-negative children, and babies with Apgar scores higher than 7 at 1 minute have increased PAPP-A concentrations. These findings are discussed in relation to PAPP-A's involvement in the maternal immunologic system.

Assay of a placental protein to determine fetal risk

Plasma concentrations and total amounts of pregnancy associated plasma protein A were determined in 272 patients at 34 weeks' gestation by immunoelectrophoretic assay. The mean plasma concentration and mean total amount of this protein were closely related (r = 0.9643) and were significantly raised in patients who subsequently developed pre-eclampsia (28 patients), went into premature labour (12), or suffered from antepartum haemorrhage (10). Mean values in all patients delivering growth-retarded babies were also raised, but when the results for such patients who also had other complications were excluded there were no differences between the sets of means. The assays were easily performed, and they may be a useful technique for screening pregnant women to detect those at risk of developing pre-eclamptic toxaemia, although the full potential of these assays cannot be realised until the protein's function is known.

Circulating levels of pregnancy specific beta 1 glycoprotein in late pregnancy: nyctohemeral and day-to-day variation, and variation during labour

Circulating levels of pregnancy-specific beta 1 glycoprotein have been determined in a number of physiological situations in late pregnancy. The apparent variation in five subjects studied over a 24-hour period was not in excess of that due to the assay. Excess variation was apparent in 2 of 11 subjects studied daily for up to 8 days, and in 6 of 16 patients studied serially during labour.

Purification and characterization of pregnancy associated plasma protein A (PAPP-A)

Pregnancy Associated Plasma Protein A (PAPP-A) has been isolated from late pregnancy plasma using ammonium sulphate precipitation, ion exchange chromatography, affinity chromatography on Concanavalin-A, gel filtration and negative affinity chromatography. It was found that PAPP-A is an alpha 2-glycoprotein of 750-820 000 MW, probably a dimer with each monomer being composed of 2 polypeptide chains of 218 000 MW. The amino acid composition as well as other physicochemical characteristics are similar to human alpha 2-macroglobulin. PAPP-A exhibits in vitro an inhibition of the activity of the complement system, of the caseinolytic activity of plasmin and possibly of the urokinase activation of plasminogen. The hypothesis that PAPP-A plays a role in the regulation of fibrinolysis during pregnancy is put forward.

Pregnancy-specific beta 1-glycoprotein (SP1) determined by means of electroimmunoassay, radial immunodiffusion and nephelometry

A comparison has been made between rocket-immunoelectrophoresis (RIE), radial immunodiffusion (RID) and automated immunonephelometry (AIP) in the assay of pregnancy-specific beta 1-glycoprotein (SP1) in serum from pregnant women. Using RIE an interaction was demonstrated between the various SP1-reactive molecular populations causing a bias of up to 10%. An interaction corresponding to this phenomenon cannot be demonstrated when using RID and AIP. When correlating the serum-SP1 concentration of samples containing various ratios of SP1-reactive molecules by means of RIE, RID and AIP, it was demonstrated that there was no correlation between the results achieved using one method compared to the results achieved by either of the other methods. The results achieved using one method can therefore exclusively be judged from reference values determined using the same method. The analysis time is essentially shorter with AIP than with RIE and RID.

Serum-SP1-pregnancy-specific-beta-glycoprotein in choriocarcinoma and other neoplastic disease

A radioimmunoassay for a plancental glycoprotein, beta1SP1, capable of detecting 2 microgram/l of the glycoprotein in serum was used to measure concentrations of beta1,SP1 in patients with choriocarcinoma, teratoma, colonic cancer, breast cancer, and ovarian cancer. 12 out of 94 (13%) healthy men and health non-pregnant women had detectable serum-beta1SP1 concentrations. Concentrations up to 50 000 microgram/l were found in the sera of patients with hydatidiform mole, invasive mole, choriocarcinoma, and malignant teratoma. beta1-glycoprotein concentrations were generally much lower than corresponding concentrations of chorionic gonadotrophin which is the most reliable marker for trophoblastic tumours. In a few cases, however, beta1-glycoprotein measurements may be useful in the detection of minimal residual tumour. The slightly raised values found in some patients with carcinoma of the colon, breast, or ovary seem unlikely to be useful for diagnostic purposes of for monitoring the course of these cancers.

Plasma concentrations of four pregnancy proteins in complications of pregnancy

Toxemia of pregnancy was associated with an elevation of the pregnancy-associated plasma protein (PAPP)-A concentration, as compared to the level in normal pregnancy in the last month of gestation. The other pregnancy proteins measured were not altered in toxemia. In twin pregnancies, the PAPP-A, PAPP-C, and human placental lactogen levels were all increased, particularly PAPP-A. On the other hand, pregnancy zone protein was not affected by twinning. Pregnancy with diabetes showed normal levels of these proteins.

Placental localization of human pregnancy--associated plasma proteins

Frozen sections of human placenta were examined for the presence of four human pregnancy proteins, pregnancy-associated plasma proteins A and C (PAPP-A and PAPP-C), human chorionic somatomammotropin (hCS), and pregnancy zone protein (PZP), by the indirect immunofluorescence technique. Monospecific rabbit antiserums to PAPP-A, PAPP-C and hCS all stained the trophoblast cytoplasm equivalently in a continuous layer, usggesting that the same trophoblast cells synthesize all three pregnancy proteins. In contrast, PZP was localized in blood vessel walls, parenchymal structures within the villous, as well as in the trophoblast cytoplasm. Its distribution in the latter was relatively inhomogeneous, tending to be more intense on the basement membrane side.

[Immunochemical investigations on the protein of the "pregnancy zone". XI. Serum concentration of the pregnancy-associated alpha2-glycoprotein (Pregnancy Zone protein) in normal pregnancy (author's transl)]

A quantitative study of the pregnancy zone proteins was made in the sera of 383 healthy pregnant women by means of radial immunodiffusion according to Mancini and co-workers. The serum levels related to a pregnancy serum standard were measured from the 6th to 44th week of pregnancy. The serum concentration of the protein showed a considerable individual variation. The mean concentration began to rise in gestational weeks 8 to 24. Until the week 32 a rather stable average level was reached. Before delivery a slight decrease was observed. Women with over term pregnancies showed particular high mean concentrations. The differences of serum levels were statistically significant until the gestational week 14.

Relation of obstetric parameters to the concentrations of four pregnancy-associated plasma proteins at term in normal gestation

The relations between normal obstetric parameters and the maternal levels of four pregnancy-associated plasma proteins (PAPP) were studied, with the use of plasma samples taken from 187 normal pregnant women within seven days before delivery. PAPP-A levels were correlated with placental and newborn weights. The levels of this pregnancy protein was higher in primigravid women and in groups with higher diastolic blood pressure than in other groups. Women with extremely high PAPP-A concentrations were likely to have extremely large placental weight was not necessarily associated with a high PAPP-A level. PAPP-C was not correlated with placental or newborn weight. The relationship between PAPP-C and maternal age, as well as maternal weight, was significant by one but not in the other three statistical analyses employed. The pregnancy zone protein was found to be correlated with parity. In primigravid women, this protein additionally showed an inverse correlation with the placental weight. Human chorionic somatomammotropin was significantly related to placental weight and inversely related to maternal weight. Its relationship with newborn weight was best seen in primigravid subjects. Other parameters (systolic blood pressure, one- and five-minute Apgar scores, weeks of gestation, days before delivery, newborn sex, and newborn bilirubin level) were not related to any of these pregnancy proteins.

Human pregnancy-associated plasma proteins during the postpartum period

The plasma levels of four pregnancy-associated plasma proteins (PAPP's) and pregnancy zone protein (PZP) were studied in women after delivery of a single viable infant by gel immunodiffussion methods. Data from 89 random samples and 85 serial specimens from five women revealed that both PAPP-B and HPL (PAPP-D) disappeared within a day after delivery. PAPP-A showed a rapid drop in the first 2 or 3 days post partum and became nondetectable in 4 to 6 weeks, with a half-life of 3 to 4 days. PAPP-C had a sharp decrease by the second postpartum day and was not detected 3 to 4 weeks later, with a half-life of 1 to 2 days. None of the PAPP's was detected again during the rest of the 14 postpartum weeks studied. In contrast, the PZP showed a much slower decrease or even a temporary increase during the first 2 weeks post partum; it remained readily detectable over the entire 14 weeks studied.

Quantitative analysis of pregnancy-associated plasma proteins in human placenta

By immunochemical methods and simultaneous measurements of several normal plasma proteins, human placenta was shown to contain elevated quantities of four pregnancy-associated plasma proteins (PAPP's). In the order of increasing amounts, PAPP-A, PAPP-C, PAPP-B, and human chorionic somatomammotropin (PAPP-D) all were present in placenta extracts in quantities greater than could be expected on the basis of their content in maternal blood. In sharp contrast, the placental content of pregnancy zone protein could be entirely accounted for by the maternal plasma present in the placenta. All of the PAPP's appeared to be readily extractible from placental tissue with buffered saline, the large bulk of them being solubilized in the first extraction procedure. However, absorption studies indicated that appreciable quantities of the PAPP's were still present in the insoluble placental residue after 12 sequential extractions with saline. The chorioamniotic membranes were not significantly enriched in any of the PAPP's. Immunochemical analysis of unwashed placental tissue extracts for the PAPP's IgA, and IgM (maternal blood derived), as well as albumin and transferrin (maternal and fetal blood derived), permitted calculations to be made of the amount of blood and PAPP's in placenta. On the basis of these data, it was roughly estimated that a 400-g placenta (wet weight) would occupy 312 ml in volume, and would contain 144 ml of blood. Of this blood, 36 ml would be derived from the mother.