Anti-trophoblast Antibodies Research Articles

Detection of Antitrophoblast Antibodies in the Sera of Patients With Anticardiolipin Antibodies and Fetal Loss

AbstractWomen with anticardiolipin antibodies (ACLA) are at increased risk for fetal loss. One potential explanation for this outcome is that sera from these individuals contain antibodies reactive with trophoblast cells, which are involved in the establishment of the uteroplacental vasculature and maintenance of placental blood fluidity. To examine this hypothesis, we compared the incidence of trophoblast-reactive antibodies in 27 patients with AC LA and a history of fetal loss with that in 29 normal pregnant women. Sera from 20 patients, but only one control, contained trophoblast-reactive antibodies (P < .001). These antibodies were not directed against major histocompatibility class I antigens, and reacted with both term and first-trimester trophoblast cells. In most cases, sera from which AC LA were adsorbed by cardiolipin-containing liposomes maintained reactivity against cells. In addition, patient Ig fractions immunoprecipitated an ~62-kD protein from the trophoblast cell surface, stimulated the release of arachi-donic acid and thromboxane A2 by trophoblasts, and inhibited the binding of prourokinase to trophoblast urokinase receptors. These observations show that sera from women with AC LA and a history of fetal loss contain antitrophoblast antibodies. These antibodies may be serologically distinct from ACLA, and may contribute to the pathogenesis of fetal demise.

Detection of antitrophoblast antibodies in the sera of patients with anticardiolipin antibodies and fetal loss

Women with anticardiolipin antibodies (ACLA) are at increased risk for fetal loss. One potential explanation for this outcome is that sera from these individuals contain antibodies reactive with trophoblast cells, which are involved in the establishment of the uteroplacental vasculature and maintenance of placental blood fluidity. To examine this hypothesis, we compared the incidence of trophoblast-reactive antibodies in 27 patients with ACLA and a history of fetal loss with that in 29 normal pregnant women. Sera from 20 patients, but only one control, contained trophoblast-reactive antibodies (P &lt; .001). These antibodies were not directed against major histocompatibility class I antigens, and reacted with both term and first-trimester trophoblast cells. In most cases, sera from which ACLA were adsorbed by cardiolipin- containing liposomes maintained reactivity against cells. In addition, patient Ig fractions immunoprecipitated an approximately 62-kD protein from the trophoblast cell surface, stimulated the release of arachidonic acid and thromboxane A2 by trophoblasts, and inhibited the binding of prourokinase to trophoblast urokinase receptors. These observations show that sera from women with ACLA and a history of fetal loss contain antitrophoblast antibodies. These antibodies may be serologically distinct from ACLA, and may contribute to the pathogenesis of fetal demise.

Isolation and characterisation of a subpopulation of human chorionic cytotrophoblast using a monoclonal anti-trophoblast antibody (NDOG2) in flow cytometry

Human cytotrophoblast cells, isolated from term amniochorion by enzymic digestion and Percoll gradient centrifugation, were characterised by flow cytometry. A panel of 12 anti-trophoblast monoclonal antibodies was screened for labelling of these cells in flow cytometry and the results compared with immunoperoxidase labelling of cytospin preparations and tissue sections. All 12 antibodies were positive for trophoblast on tissue sections, 11 12 were positive on cytospins but only two (NDOG2 and GB25) gave consistent results in flow cytometry. Two-colour labelling with NDOG2 and W6/32, an antibody to HLA-A, -B, -C, demonstrated that 88% of the NDOG2-positive cells also express Class I major histocompatibility complex (MHC) antigens. The NDOG2-positive cytotrophoblast subpopulation was isolated by flow cytometry in sufficient purity (>95%) and yield (3.1 × 10 6) for use in functional studies in vitro.

Effect of anti-trophoblast antibodies on one way maternofetal mixed lymphocyte reaction

Effect of anti-trophoblast antibodies on one way maternofetal mixed lymphocyte reaction

Identification of selectively solubilised syncytiotrophoblast plasma membrane proteins as potential antigenic targets during normal human pregnancy

Syncytiotrophoblast plasma membranes prepared from term placentae were selectively solubilised in non-ionic detergents. The solubilised proteins and the insoluble residue were tested in an ELISA assay for their ability to function as antigenic targets for anti-trophoblast antibodies present in normal first trimester pregnancy sera. The soluble proteins were fractionated by gel filtration and four major antigen forms were identified. The antigens were reactive with affinity purified anti-trophoblast antibody isolated from maternal sera and hence were termed maternally-recognised trophoblast antigens (MRTA); these were designated MRTA-I ( M r = 400, 000 D, MRTA-II ( M r = 142, 000), MRTA-III ( M r = 50, 000), and MRTA-IV ( M r = 13, 000). The relationship between MRTA-I, II, III and IV and antigens identified in maternal sera in the form of immune complexes is discussed.

Anti-trophoblast antibody responses during normal human pregnancy

During the course of a normal uncomplicated human pregnancy the mother generates an antibody response directed against determinants present on the plasma membrane of the outer fetal layer of the term placenta, the syncytiotrophoblast. The response, measured by an ELISA that utilises syncytiotrophoblast plasma membrane as the antigenic target, is predominantly IgG in nature, but with a minor contribution from IgM molecules. Maximum responses were observed during the first trimester and the levels gradually declined as the pregnancy progressed. On a population basis, this antibody response profile was mainly restricted to first and second pregnancies, although anti-trophoblast antibody responses could be detected in multiparous women but with a greatly reduced incidence compared with primipara. Mechanisms to account for these observations are discussed. Throughout, the anti-trophoblast antibody levels detected in pregnancy sera were compared with the background levels which were observed in sera obtained from males and nulliparous non-pregnant females.

Immunocytochemical identification of cytotrophoblast from other mononuclear cell populations isolated from first-trimester human chorionic villi.

Trophoblast biologists are often uncertain as to what cell types they are investigating because the mononuclear cell populations prepared from trypsinization of human first-trimester chorionic villi are morphologically very similar. In the present study, immunocytochemical and phagocytic markers have been used to distinguish cytotrophoblast populations from cell types derived from the mesenchyme of the chorionic villus. Two anti-trophoblast monoclonal antibodies generated in our own laboratory (18B/A5 and 18A/C4) were found to be very efficient in identifying cytotrophoblast, which made up 35-40% of the cells in a smear. Most cytotrophoblast cells did not stain with a monoclonal anti-HLA-A,B,C antibody but a few cells (5%) were found to express both trophoblast and HLA-A,B,C antigens by a double-labelling technique. Endothelial cells from villous capillaries could be identified by a rabbit anti-factor VIII antibody. These cells formed 28% of the population in a cytospin smear. Macrophages from the villous mesenchyme were less readily separable as neither specific monoclonal antibodies nor localization of enzymes were found to be effective. However, these cells could be identified by their ability to phagocytose carmine. About 15% of the cells in a smear consisted of macrophages. The procedure described should prove useful in judging the efficiency of isolation methods from human placental cells.

An ELISA for the detection of maternal anti-trophoblast antibodies in human pregnancy

An ELISA has been developed which is able to detect antibodies directed against determinants present on the plasma membrane of the outer layer, the syncytiotrophoblast, of term placentae. The IgG and IgM anti-trophoblast antibodies are present in the sera of women during the course of a normal pregnancy. The ELISA was based on the use of syncytiotrophoblast plasma membranes as the antigenic targets and utilised a developing antiserum conjugated to the bacterial enzyme urease. Although the assay was simple and reproducible, its viability was dependent on several factors including the stability of the antibodies and the proper preparative techniques for the production of the plasma membranes. Failure to adhere to the correct procedures resulted in an inferior non-viable assay.

The formation of immune complexes in primiparous and multiparous human pregnancies

Using a recently developed ELISA, antibodies were detected in maternal sera with reactivity directed against determinants present on the plasma membrane of the outer layer of the placenta, the syncytiotrophoblast. The anti-trophoblast antibodies were present in maternal sera in the form of “free” antibodies and “immune complex” antibodies. Examination of the sera throughout gestation and from successive pregnancies revealed that the generation of anti-trophoblast antibodies and the formation of immune complexes was predominantly a first pregnancy and early second pregnancy event, with very little activity detectable in later pregnancies. It is proposed that immune recognition occurs in a first pregnancy, which generates some form of immunosuppression that involves the activation of suppressor memory cells.

An investigation of trophoblast iso-immunization in normal pregnancy.

Summary: There has been widespread interest in the survival of the mammalian placenta as an allograft and in the possibility that humoral isoimmunization against placental antigens might occur in normal pregnancy.In this study, an indirect immunofluorescent test for circulating antitrophoblast antibodies failed to confirm previous reports of their presence in the serum of pregnant and postpartum women. An incidental, but common and non‐specific immunofluorescent staining characteristic of extra‐cellular fibrinoid material was demonstrated in sections of early placenta and to a lesser degree in late placenta.