Pregnancy-specific Beta 1-glycoprotein Research Articles

Pregnancy-specific beta 1-glycoprotein in serum in monoclonal gammopathies: relationship with serum beta 2-microglobulin, and cellular origin.

Pregnancy-specific beta 1-glycoprotein (SP1) was assayed by particle-counting immunoassay in serum from 86 healthy blood donors and 236 patients with various types of gammopathy. A concentration of 1 microgram/L was taken as the upper normal limit. Abnormally high values were found in one of 10 patients with monoclonal gammopathy of undetermined significance, in 65% of 152 patients with multiple myeloma, in 84% of 64 patients with Waldenström's macroglobulinemia, and in seven of 10 patients with monoclonal gammopathies associated with other myeloproliferative disorders. In a study of 90 myeloma patients, the SP1 value correlated (p less than 0.001) with the concentration of beta 2-microglobulin in serum, a value which had been corrected for possible renal dysfunction, but not with the concentration of the monoclonal component. SP1 was detected by direct immunofluorescence in myeloma cells of bone-marrow smears from six of 10 patients with myelomatosis. These six patients had serum SP1 values greater than 1 microgram/L, whereas the four patients with fluorescence-negative myeloma cells had SP1 values less than 1 microgram/L.

Pregnancy-specific beta 1-glycoprotein concentrations throughout pregnancy in the rhesus monkey.

Proteins that are immunologically related to human pregnancy-specific beta 1-glycoprotein (hSP1) have been detected in serum samples from pregnant subhuman primates. However, little information is available concerning the concentrations or secretory dynamics of SP1 in nonhuman primate pregnancy. To examine serum SP1 concentrations throughout rhesus monkey gestation, a heterologous RIA for rhesus SP1 (rSP1) was developed which used an antiserum against rSP1 and purified human SP1 as the standard and for iodination. No rSP1 was detected in serum samples from 8 normal male monkeys, 8 castrated females, or 10 regularly cycling females. Levels of rSP1 were measured in 260 serum samples from 43 pregnant monkeys. rSP1 was first detected on day 14 after mating, and all monkeys sampled 25 or more days after mating had detectable serum rSP1 levels. Serum rSP1 rose exponentially from day 14 to about day 50, followed by a more gradual rise until term. This pattern of secretion was in marked contrast to that found for macaque CG, which was already detectable 10 days after mating, peaked at 20 days, and returned to nonpregnant levels by day 40. The disappearance of rSP1 after delivery was best fit by a 2-component 4-parameter model with a mean residence time of 48 h. These data indicate that the pattern of rSP1 secretion throughout pregnancy is qualitatively similar to that found for hSP1, as is the long half-life of the protein in the circulation after delivery. rSP1 measurements may provide a useful index of placental function during rhesus pregnancy and serve as a model to study the biological role of SP1 in primates.

Serum proteins in vesicular fluid of hydatidiform moles: a lack of selectivity of molar trophoblast in the transfer of maternal serum proteins

Complete hydatidiform moles, an abnormal pregnancy of androgenetic origin consisting of swollen villi without an embryo, were studied to determine the protein constitution of vesicular fluids in the swollen villi and the ability of the molar tissue to synthesize protein. All 16 serum proteins tested were identified in the molar fluid. A reverse correlation was obtained when the logarithms of the molar fluid versus maternal serum concentration ratios of different proteins were plotted against the logarithms of their molecular weights. Logarithmic regression analysis showed a linear regression with a high coefficient (gamma = 0.9626). Phenotyping of haptoglobin in the molar fluid and in the parental sera indicated a definite contribution of maternal proteins to the molar fluid. The molar tissues synthesized no serum proteins but produced human chorionic gonadotrophin beta-subunit (hCG-beta) and pregnancy-specific beta 1-glycoprotein (SP1) when examined in tissue cultures metabolically labelled with [35S]methionine. These findings indicate that a variety of maternal serum protein components is transferred to the molar fluid without being selected by the molar trophoblastic cells.

Trophoblastic proteins as tumor markers in nonseminomatous germ cell tumors

In order to examine the relative usefulness of measurements of oncoplacental proteins as tumor markers in patients with nonseminomatous germ cell tumors, the authors measured alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), pregnancy-specific beta 1-glycoprotein (SP1), human placental lactogen (hPL), and placental cystine aminopeptidase (oxytocinase, CAP) in serial blood samples obtained from 26 men with these neoplasms. HCG and AFP were each elevated in 62% of the patients and both were elevated in 38%. SP1 and hPL were increased in 31% and 12%, respectively. None of the patients had elevated CAP activity. Serum hCG and SP1 concentrations were strongly correlated (r = 0.78, P less than 0.001). No patient had an elevated SP1 without a concomitant elevation in serum hCG. Serial measurements of hCG and SP1 indicated that they were concordant in five of the eight patients in whom both were elevated, and AFP and hCG were concordant in only one half of the ten patients in whom both markers were elevated. The number of patients with hPL elevations were too few for meaningful comparison of this marker with the others. These results indicate that measurements of SP1, hPL, and CAP do not provide additional useful information over that obtained from measurements of hCG and AFP in patients with nonseminomatous germ cell tumors.

Purification, characterization, and in vitro differentiation of cytotrophoblasts from human term placentae.

Highly purified functional cytotrophoblasts have been prepared from human term placentae by adding a Percoll gradient centrifugation step to a standard trypsin-DNase dispersion method. The isolated mononuclear trophoblasts averaged 10 microns in diameter, with occasional cells measuring up to 20-30 microns. Viability was greater than 90%. Transmission electron microscopy revealed that the cells had fine structural features typical of trophoblasts. In contrast to syncytial trophoblasts of intact term placentae, these cells did not stain for hCG, human placental lactogen, pregnancy-specific beta 1-glycoprotein or low mol wt cytokeratins by immunoperoxidase methods. Endothelial cells, fibroblasts, or macrophages did not contaminate the purified cytotrophoblasts, as evidenced by the lack of immunoperoxidase staining with antibodies against vimentin or alpha 1-antichymotrypsin. The cells produced progesterone (1 ng/10(6) cells . 4 h), and progesterone synthesis was stimulated up to 8-fold in the presence of 25-hydroxycholesterol (20 micrograms/ml). They also produced estrogens (1360 pg/10(6) cells . 4 h) when supplied with androstenedione (1 ng/ml) as a precursor. When placed in culture, the cytotrophoblasts consistently formed aggregates, which subsequently transformed into syncytia within 24-48 h after plating. Time lapse cinematography revealed that this process occurred by cell fusion. The presumptive syncytial groups were proven to be true syncytia by microinjection of fluorescently labeled alpha-actinin, which diffused completely throughout the syncytial cytoplasm within 30 min. Immunoperoxidase staining of cultured trophoblasts between 3.5 and 72 h after plating revealed a progressive increase in cytoplasmic pregnancy-specific beta 1-glycoprotein, hCG, and human placental lactogen concomitant with increasing numbers of aggregates and syncytia. At all time points examined, occasional single cells positive for these markers were identified. RIA of the spent culture media for hCG revealed a significant increase in secreted hCG, paralleling the increase in hCG-positive cells and syncytia identified by immunoperoxidase methods. We conclude that human cytotrophoblasts differentiate in culture and fuse to form functional syncytiotrophoblasts.

Synthesis of Placental Proteins by the Human Placenta Perfused in vitro

Fresh human placental tissue from deliveries at term was perfused in closed circulation on both the maternal and fetal side. At given times during the 4-hour perfusion period, the amount of human chorionic gonadotropin, human placental lactogen, pregnancy-specific beta 1-glycoprotein and pregnancy-associated plasma protein A was determined in the perfusing buffer. These placental proteins were also quantified in the placental tissue before and after perfusion. Calculations showed that all placentae (n = 3) were able to synthesize all 4 proteins tested.

Immunohistochemical Characterisation of Trophoblast Antigens and Secretory Products in Ectopic Tubal Pregnancy

Fetal trophoblast populations in ectopic fallopian tube pregnancy have been characterised using immunohistochemical techniques. The distribution of trophoblast membrane antigens, low molecular weight epithelial cytokeratins, epithelial membrane antigen, human chorionic gonadotrophin, human placental lactogen, and pregnancy-specific beta 1-glycoprotein in ectopic tubal pregnancy appears similar to that reported in normal early intrauterine pregnancy. These findings emphasise the potential importance of ectopic pregnancy in the study of human gestation.

Clinical Value of Pregnancy‐Specific β1‐Glycoprotein (SP1) and β‐hCG Determination in Serum in Suspected Ectopic Pregnancy

We compared the clinical value of pregnancy-specific beta 1-glycoprotein (SP1) determination in serum by means of a highly sensitive enzyme-linked immunosorbent assay (ELISA) versus that of beta human chorionic gonadotropin (beta-hCG) determination in suspected ectopic pregnancy. The study comprised 58 women admitted consecutively with suspected ectopic pregnancy but without signs warranting immediate surgical intervention. Both SP1 and beta-hCG were found in 11 patients with ectopic pregnancy and in 8 patients with early intra-uterine pregnancy, whereas beta-hCG was detected in 4 and SP1 in 7 of 8 women with a recent abortion. Of 31 women presenting a non-pregnant condition, 2 were positive for both SP1 and beta-hCG. The measurement of SP1 in serum thus appears to be an alternative to beta-hCG measurement when ectopic pregnancy is suspected.

Prognostic value of concentration of pregnancy-specific beta 1-glycoprotein (SP1) in serum of patients with breast cancer.

Pregnancy-specific beta 1-glycoprotein (SP1) was assayed by particle counting immunoassay in serum from 46 healthy female blood donors, 33 patients with benign mastopathy and 84 patients with breast cancer before operation and during follow-up. Values greater than 1 micrograms/1 were found more frequently with benign mastopathies (11/33) and in patients with breast cancer at stage 2 (20/48), 3 (4/9), and 4 (7/10) than in healthy female blood donors (3/46). The survival rate after 4 years was significantly lower in patients with SP1 level greater than 1 microgram/1 before tumor resection (52% vs. 87%). The difference remained significant when only patients in stage 2 were taken into account (57% vs. 85%). A highly significant (r = 0.64; N = 46) negative correlation was observed between the concentration of SP1 in serum and the concentration of estrogen receptor in the tumor. The longitudinal study of patients in stage 2 indicated that, of the 15 whose SP1 concentration fell below 1 microgram/1 after operation, 14 survived over 4 years whereas during the same period, 9 of the 10 patients whose SP1 value remained higher than 1 microgram/1 died.

The immunohistochemical localization of pregnancy-specific β1-glycoprotein in postimplantation rat trophoblast

Pregnancy-specific beta 1-glycoprotein (SP1) was identified by peroxidase-antiperoxidase (PAP) immunohistochemistry in the placenta of inbred strains of rat between 10 and 21 days of gestation. SP1 was located predominantly in basal zone trophoblast and in intravascular trophoblast of decidual vessels, but it was absent from labyrinthine trophoblast. No perivascular cells were identified by SP1 staining, but occasional clusters of interstitial trophoblast stained for SP1. The results suggest that basal and labyrinthine trophoblast are functionally different.

Monitoring of postimplantation embryo viability following successful in vitro fertilization and embryo transfer by measurement of placental proteins

Serum levels of pregnancy-associated plasma protein A (PAPP-A), human chorionic gonadotropin (hCG), and pregnancy-specific beta 1-glycoprotein (SP1) were measured in 21 women after successful in vitro fertilization and embryo transfer. Of the 21 pregnancies, 14, including 1 twin gestation, progressed successfully to term. The remaining seven, composed of tubal (n = 3), anembryonic (n = 1), and spontaneously aborted (n = 3) pregnancies, failed during the first half of pregnancy. Placental protein measurement was of no diagnostic value in the detection of anembryonic pregnancy. Similarly, measurement of hCG and SP1 could not readily distinguish tubal ectopic from normal intrauterine pregnancies. By contrast, the predictive value (38.9%) of a depressed PAPP-A level in conjunction with superior diagnostic sensitivity (70%) and relative risk factor (23.6) proved to be of greater diagnostic value in this potentially lethal condition. In the absence of ultrasonography, the biochemical diagnostic indices were comparable in the prediction of spontaneous abortion. However, in the presence of a live fetus, PAPP-A levels were consistently depressed (sensitivity, 91.7%) many weeks before pregnancy demise. The relative risk factor of depressed PAPP-A levels was 29 times greater than the risk associated with a depressed hCG level. These findings further demonstrate the potential diagnostic value of PAPP-A measurement for monitoring postimplantation embryo viability.

Development and characterization of monoclonal antibodies to pregnancy-specific beta 1-glycoprotein.

Six monoclonal antibodies were developed to pregnancy-specific beta 1-glycoprotein (PS beta 1G). Studies of ascitic fluid antibodies by a double-antibody radioimmunoassay (RIA) included an evaluation of titers, dose-response parameters, and mass action properties. Four of the antibodies demonstrated moderate to high titers ranging from 1/40 000 to greater than 1/120 000, as determined by the specific binding of 125I-labeled PS beta 1G. In inhibition studies utilizing a standard containing known quantities of placental PS beta 1G, two of the antibodies (AR#11 and B#2) were highly sensitive and only slightly lower in this regard than a high affinity polyclonal antiserum. The binding affinities of AR#11 and B#2 monoclonals were greater than 10(9) mol-1 which underline their importance as potential clinical reagents for the RIA of PS beta 1G. The Scatchard plots, for several of the antibodies, were linear and in full agreement with a single order of binding sites predicted for specific monoclonal reagents. Immunodiffusion results provide preliminary evidence that at least three distinct determinants on PS beta 1G are recognized by a number of the monoclonal antibodies. Further studies on the fine specificities of the antibodies by solid-phase RIA, as well as a detailed evaluation of their clinical applications, are in progress.

Evidence for the presence of oncoplacental SP1-like protein in normal nonpregnant serum.

To seek the pregnancy-specific beta 1-glycoprotein (SP1) in nonpregnant serum, normal human serum was applied to immunoadsorbent containing monoclonal anti-SP1 antibodies. SP1 eluted with 8 M urea was further analyzed by sodium dodecyl sulfate-gel electrophoresis and immunoblotting. A SP1-positive band with the same electrophoretic mobility as purified placental SP1 was found. The results suggest that serum from normal nonpregnant subjects contains material closely related to the placental protein SP1. The mean serum concentrations of SP1 were similar in men and women, ranging from 1.1-3.4 ng/ml.

Do pregnancy proteins have prospective significance? (SP-1, HPL and PP-5)

Concentrations of pregnancy proteins were determined in blood of 219 pregnant women in 20th week of gestation. Pregnancy-specific beta 1-glycoprotein SP-1, human placental lactogen (hPL) and placental protein 5 (PP-5) were tested. In contrast with results of other authors there were no differences between the normal group of patients and those with complications during gestation, such as prematurity and foetal retardation. Thus measurement of blood concentration of proteins mentioned above in 20th week is not of prognostic relevance for gestation.

Monitoring of Postimplantation Embryo Viability by Measurement of PAPP‐A, SP1, and hCG

After successful in vitro fertilization and embryo transfer, chorionic gonadotropin, pregnancy-specific beta 1-glycoprotein, and pregnancy-associated plasma protein-A were measured in serum samples collected serially from 21 patients. While 14 pregnancies, including one twin pregnancy, progressed successfully to term, the remaining seven pregnancies failed during the first half of gestation. This latter group consisted of three tubally implanted, one anembryonic, and three spontaneously aborted pregnancies. Circulating levels of hCG, SP1, and PAPP-A in the patient with an anembryonic pregnancy were within normal limits. Similarly, 90.5% of the serum samples obtained from women with tubal pregnancies showed hCG levels within normal limits. By contrast, only two of these samples had detectable PAPP-A, of which only one was within normal limits. Of the samples obtained from the patients who spontaneously aborted, including one patient with normal ultrasonic findings up to 48 hours prior to the event, 85.7% had PAPP-A concentration below the 10th percentile, whereas only 16.7% of these samples showed depressed hCG levels. These data suggest that PAPP-A measurement has great clinical potential in the management of compromised early pregnancies.

Particle-counting immunoassay (PACIA) of pregnancy-specific beta 1-glycoprotein, a possible marker of various malignancies and Crohn's ileitis.

Pregnancy-specific beta 1-glycoprotein (SP1) was assayed by particle-counting immunoassay (PACIA) with a sensitivity of 1 microgram/L. In serum from 50 men, the SP1 concentration was less than 1 microgram/L, whereas three of the specimens from 46 nonpregnant women had values exceeding 1 microgram/L. In 29% of 950 consecutive patients' sera, SP1 concentrations exceeded 1 microgram/L--in sarcoma (six of six), in malignant hemopathies (101/127, 80%) such as myeloma (20/26, 92%) and acute myeloblastic leukemia (23/27, 90%), and in various other types of cancer (11/19, 58%) except for bronchial epithelioma, which did not lead to any significant increase of SP1 in the five patients examined. The concentration of SP1 was also frequently increased in patients with Crohn's ileitis (28/43, 65%) but not in patients with other inflammatory disorders.

Periovulatory secretion of immunoactive 03 pregnancy-specific β 1- glycoprotein(SP 1) in humans: Comparison with « normal » SP 1

The pregnancy-specific beta 1-glycoprotein (SP1)-immunoreacting material in serum from two patients around ovulation was compared with serum SP1 activity derived from normal pregnant women. This was done by antibody binding experiments, density gradients and binding to lentil lectin. Periovulatory SP1 behaved similarly to SP1 from pregnant patients. It is therefore suggested that the periovulatory immunoreacting material is true SP1 and that this protein, though rarely, can be synthesized outside the trophoblast in healthy women.

Immunohistochemical and radioimmunological determination of beta-HCG and pregnancy-specific beta 1-protein in seminomas.

38 pure and 11 mixed seminomas were studied with the peroxidase-anti-peroxidase method for the presence of chorionic gonadotropin (beta-HCG) and pregnancy-specific beta 1-glycoprotein (SP1). HCG was found in 8 of 49 cases, SP1 in 5 of 49 cases in syncytial and mononuclear giant cells. The 5 pure seminomas with positive tumor markers appear to have no worse prognosis than pure seminomas without HCG or SP1 production. None of the seminomas was found to contain carcinoembryonic antigen or alpha-fetoprotein.

Fibrin-fibrinogen degradation products and pregnancy-specific beta 1-glycoprotein (SP 1) in normal and pathological pregnancies

Fibrin-fibrinogen degradation products and SP 1 were measured in about 150 women with normal pregnancies. The mean levels of both parameters rose up to term. In 13 normal pregnancies the SP 1 course never decreased. Elevated levels of SP 1 were measured in 4 out of 10 cases of mild gestosis. In 11 cases of severe gestosis, however, 7 had increased values. A decrease of elevated levels correlated to a clinical deterioration. SP 1 was normal in the most cases of severe gestosis, but a fall of SP 1 indicated an impaired placental function resulting in small-for-date baby or imminent foetal asphyxia. The measurements of fibrinogen degradation products and of the course of SP 1 are helpful in the diagnosis of gestosis.

Correlation of immunohistochemical markers with patient prognosis in breast carcinoma: a quantitative study.

In a series of 46 cases of primary mammary ductal carcinoma, immunohistochemical markers of differentiation (casein, human placental lactogen, alphalactalbumin, pregnancy specific beta-1 glycoprotein, secretory component, CEA, and peanut lectin agglutinins [PLA]), were quantitated via point-counting. An immunoperoxidase bridge (PAP) was used to identify all except the PLA, in which an avidin-biotin complex with alkaline phosphatase development was employed. For none of the markers was there any difference in the quantity present in tumors of patients who had recurred versus the tumors of patients who had enjoyed a minimum of five years disease-free survival. Nonneoplastic epithelium was only rarely positive for these markers. Although eventually surmounted, technical problems significantly hampered application of morphometry to this histochemical material. The authors conclude that these markers have little relationship to differentiation toward mammary duct epithelium and that they do not provide significant prognostic information in patients with breast cancer.