The placental site nodule: An immunohistochemical study

The placental site nodule and plaque (PSN-P) is a recently described, benign proliferation of intermediate trophoblast cells (ITs) in the endometrium or endocervix occurring after an intrauterine gestation. We performed an extensive immunohistochemical study of 11 cases of PSN-P. Cytokeratins ( and MAK 6) were strongly positive in all cases stained. Epithelial membrane antigen (EMA) was positive in all cases, in 5% to 75% of lesional cells. Expression of human placental lactogen (hPL) was weak and focal, and a minority of cases were positive for human chorionic gonadotropin (hCG). More helpful in identifying the trophoblastic nature of the lesion was pregnancy-specific beta-1 glycoprotein (SP1), which was present in 100% of cases, and placental alkaline phosphatase (PLAP), present at least focally in 90% of cases stained. Vimentin was strongly positive in all cases stained. The presence of vimentin, SP1, and PLAP in PSN-P has not been documented previously. In our opinion cytokeratin, vimentin, and SP-1 are the most important monoclonal antibodies to aid in the differential diagnosis of PSN-P.     

Endothelial nitric oxide synthase immunoreactivity in early gestation and in trophoblastic disease.

AIMS: To study the localisation of the endothelial nitric oxide synthase (eNOS) in the normal placenta, with special emphasis on the implantation site in the first trimester of pregnancy, and in the different subtypes of trophoblastic cells in gestational trophoblastic disease. METHODS: The immunoperoxidase technique with an antibody directed against eNOS was applied to paraffin sections from first and second trimester placentas, placenta accreta, partial and complete hydatidiform moles, and choriocarcinoma. Immunoperoxidase staining for human placental lactogen (hPL) was performed on parallel sections. RESULTS: Prominent immunoreactivity for eNOS was found to be present in the intermediate trophoblastic cells of the cell columns of the anchoring villi and in trophoblastic cells at the implantation site. Staining was also present in the syncytiotrophoblast, most conspicuous at the apical cell border. In trophoblastic disease, proliferating large mononuclear cells, which were strongly positive for hPL, were found to be immunoreactive for eNOS. CONCLUSIONS: eNOS immunoreactivity is strongly positive in the extravillous trophoblastic cells and to a lesser extent in the syncytiotrophoblast. In the former it may play a role in implantation and vascular invasion. Cells with differentiation to intermediate trophoblast in complete hydatidiform mole and choriocarcinoma also show high levels of eNOS, which may be associated with the haematogenous mode of spread of trophoblastic disease.     

Immunoelectron microscope observations on secretion of human placental lactogen (hPL) in the human chorionic villi

Immunoelectron microscope localization of human placental lactogen (hPL) was investigated in the chorionic villi from week 7 to full-term gestation with the protein A-gold technique. With specific antiserum against hPL, immuno-reactive gold particles were found to be preferentially located in Golgi-derived, electron-dense small granules of 80-180 nm in the syncytiotrophoblast. Our electron micrographs indicate that these small granules increase in number in the course of gestation and are released by exocytosis from the apical cell surface. The present study reveals that hPL is segregated from the Golgi apparatus, stored in the syncytiotrophoblast as secretory granules, and released into the maternal blood.     

Immunohistochemical localization of interferons in human placental tissues in normal, ectopic, and molar pregnancy

Interferon (IFN)alpha, beta, and gamma have been localized in normal and pathological human pregnancy using both polyclonal and monoclonal antibodies in immunohistochemical techniques. IFN alpha was localized to fetal chorionic villous syncytiotrophoblast throughout normal pregnancy, as well as to extravillous trophoblast in the placental bed and chorion lave. Maternal decidual leukocytes, as well as fetal Hofbauer cells in the villous mesenchyme, also contained IFN alpha, IFN gamma was detected in villous syncytiotrophoblast, while anti-IFN beta showed only patchy weak reactivity with syncytiotrophoblast. Reaction patterns on ectopic pregnancy tissues were similar to those in early intrauterine pregnancy. In molar pregnancy, reactivity for IFN alpha, beta, and gamma was observed in syncytiotrophoblast. Along with their potential anti-viral effects, placental interferons could play a role in local immunomodulation or in regulation of embryonic cell proliferation and differentiation.     

The use of cytokeratin as a sensitive and reliable marker for trophoblastic tissue.

The use of human chorionic gonadotropin (hCG), human placental lactogen (hPL), and pregnancy-specific beta-1-glycoprotein (SP1) as markers for trophoblastic tissue is well documented in the literature. However, it is not widely recognized that cytokeratin is a very sensitive and reliable marker for all types of trophoblastic tissues. The authors have studied 100 cases of human placental tissue ranging in age from 2 to 40 weeks. Unlike hCG and hPL, which stain only the syncytiotrophoblast and intermediate trophoblast, cytokeratin (AE1/AE3) stains all three types of trophoblastic tissue. The staining of placental tissue for cytokeratin is strong and very consistent throughout pregnancy. Because of its high sensitivity and ability to stain cytotrophoblast, it is believed that it could be very useful in the study of the pathologic process of implantation sites, especially in tissue obtained from patients who present with missed and habitual abortions.     

“Placental polyp”: Light microscopic and immunohistochemical observations

A case of the chronic type of placental polyp, occurring in a 37-year-old woman approximately 9 years after abortion of her last known pregnancy, is reported. The placental polyp was predominantly composed of necrotic and hyalinized chorionic villi without identifiable lining trophoblast; however, some villi showed a thin rim of apparently viable syncytiotrophoblast that exhibited focal strong positivity for human chorionic gonadotropin by immunohistochemical studies. Intermediate trophoblast, especially abundant within the intervillous fibrin, appeared most viable and showed strong positivity for human placental lactogen (hPL); syncytiotrophoblast also showed focal positivity for hPL. The basal aspect of the polyp was composed of abundant decidua that contained dilated and ectatic blood vessels. This study demonstrates the presence of cytoplasmic markers for pregnancy in a chronic type of placental polyp, apparently of 9 years' duration, and draws attention to an entity that may be encountered more frequently due to the current prevalence of induced abortions.     

Isolation of antibody to human placental alkaline phosphatase (PLAP) from extracts of human placentae

PROBLEM: Human placental alkaline phosphatase (PLAP) is a unique placental antigen bound to the syncytiotrophoblast, which may be able to elicit a specific immune response in pregnancy. METHOD OF STUDY: Antibody to PLAP was purified from placental extracts by: a) acid elution of membrane vesicles; b) purifying complexes of PLAP with human antibody on monoclonal antibodies to PLAP followed by denaturation of the enzyme; and c) by denaturation of PLAP in placental extracts and purification of antibody to PLAP on PLAP columns. RESULTS AND CONCLUSIONS: Specific antibody to PLAP is present in placental extracts, and is mostly bound to placental membrane preparations. PLAP is therefore immunogenic in pregnancy and could serve as a useful monitor of pregnancy-specific immunological responses. Since a similar enzyme appears in some cancers, it is possible that the immunization against PLAP in pregnancy will help to protect against the development of ovarian and endometrial cancer (the 'fetal antigen' hypothesis).     

The production and characterisation of monoclonal antibodies against human prolactin and the development of a two-site immunoradiometric assay

Monoclonal antibodies against human prolactin (PRL) have been produced and characterised and used to develop a sensitive two-site immunoradiometric assay (IRMA). Nine anti-PRL monoclonal antibodies were assessed for reactivity in immunoblotting experiments with PRL, hPL, hGH and pituitary gland extract. There was no detectable crossreactivity with hPL or hGH. In liquid phase radioimmunoassay (RIA) studies using three of the antibodies there was no detectable crossreaction from hPL or hGH. Five antibodies were positive in immunocytochemical studies using sections of human pituitary gland. Using FPLC purified monoclonal antibodies, a two-site IRMA was developed that could assay PRL over the range 17.5-3500 mIU per litre and was readily adapted to assaying serum samples from patients. The two-site IRMA could be performed within one day without loss of sensitivity and has potential as a rapid and simple method for screening clinical samples.     

Expression of epidermal growth factor receptor and transferrin receptor by human trophoblast populations

Epidermal growth factor (EGF) has several roles, including stimulation of cell division and differentiation. EGF receptor (EGFR) has been localized to villous syncytiotrophoblast, but expression by other human trophoblast populations has not been reported. EGFR expression was examined in normal and pathological placental tissues using a streptavidin-biotin-peroxidase technique; results were compared with expression of transferrin receptor (Tf-R) in similar tissues. EGFR was detected on villous syncytiotrophoblast in early and term pregnancy with labelling of the apical membrane, focal cytoplasmic reactivity, and patchy labelling of the trophoblast basement membrane. In contrast with other reports, EGFR was also consistently localized to villous cytotrophoblast, chorion laeve, and extravillous trophoblast populations in maternal uterine tissues. Maternal decidua showed diffuse labelling of stromal cells, particularly in the superficial zones. The reaction pattern in ectopic tubal pregnancy was similar to that in early intrauterine pregnancy. In molar pregnancy, EGFR was detected on villous syncytiotrophoblast and cytotrophoblast. In contrast, in normal, ectopic, and molar pregnancies labelling for Tf-R was confined to syncytiotrophoblast and to the proximal portions of the cytotrophoblast columns. Expression of EGFR by all trophoblast cells may represent a mechanism of placental growth and proliferation control. EGFR may also be involved with establishment of differentiated trophoblast functions including hormone secretion.     

Distribution of Fc gamma receptors on trophoblast during human placental development: an immunohistochemical and immunoblotting study.

Expression of Fc gamma receptors on human placental trophoblast was investigated by immunostaining and immunoblotting using a panel of Fc gamma receptor monoclonal antibodies (mAb). Fc gamma receptors typical of other cell types were not detected on syncytiotrophoblast in term placentae when transplacental IgG transport was maximal. Unexpectedly, however, and by contrast with term, all Fc gamma receptor III mAb tested bound to first trimester placental syncytiotrophoblast by immunostaining. Reactivity was relatively restricted and varied between specimens. Fc gamma receptor III products of 41,000-45,000 and 49,000-52,000 MW were consistently detected on first trimester trophoblast membranes by immunoblotting and levels of these products were greatly reduced following treatment with phosphatidylinositol-specific phospholipase C, suggesting that the early trophoblast Fc gamma receptor III is glycosyl-phosphatidylinositol (GPI) linked. The mAb Leu-11b behaved differently to other anti-Fc gamma receptor III mAb examined. By immunostaining, Leu-11b bound to syncytiotrophoblast at term and detected both syncytiotrophoblast and underlying cytotrophoblast in the first trimester. In addition to the GPI-anchored Fc gamma receptor III in first trimester, Leu-11b also detected a 74,000 MW component on both first trimester and term trophoblast membranes by immunoblotting. Thus trophoblast appears to express a GPI-anchored Fc gamma receptor III in first trimester but not term placentae. With the exception of the 74,000 MW Leu-11b-defined product whose function is unclear, currently available Fc gamma receptor mAb appear to be incapable of detecting the protein involved in IgG transport during the later stages of gestation.     

A unifying concept of trophoblastic differentiation and malignancy defined by biomarker expression

Several trophoblast phenotypes, including cytotrophoblast, syncytiotrophoblast, and extravillous trophoblast, emerge during gestation. To clarify the lineage relationship between these subtypes, we profiled p63 localization in developing and term placental tissue, as well as in trophoblastic tumors, using antibodies specific to full-length (TAp63) and one against all p63 isoforms (TAp63 and DeltaNp63). Localization of p63 was compared with that of biomarkers of proliferation and trophoblastic differentiation, including mib-1, inhibin, and MelCAM. In early gestation, p63 was localized principally to villous cytotrophoblast after contact with the villous mesenchyme, absent in the trophoblast columns, and early implantation trophoblast. In the maturing placenta, intraplacental perivillous fibrin correlated with the emergence of a p63-positive "transitional" (vacuolated) extravillous trophoblast from cytotrophoblast, which differentiated further into a "mature" p63-negative extravillous trophoblast. The same lineage pathway emerged from entrapped villi on the chorionic membrane. Virtually all p63 immunopositivity was attributed to dominant-negative p63. The immunophenotypic patterns seen in the immature and mature placenta permit the resolution of all trophoblastic phenotypes within 3 lineage pathways of cytotrophoblast differentiation, including cytotrophoblast-to-trophoblast column/implantation site, cytotrophoblast-to-syncytiotrophoblast, and cytotrophoblast-to-mature extravillous trophoblast. In the latter pathway, a transitional (vacuolated) p63-positive extravillous trophoblast emerges from and links cytotrophoblast to mature extravillous trophoblast in intraplacental fibrin, chorionic membrane, and basal plate. The placental trophoblast is thus resolved within this continuum of differentiation. Terms such as transitional and mature extravillous trophoblast are proposed to reflect the differentiation phases of this unique epithelium. p63 staining patterns in trophoblastic tumors reflect timing of neoplastic transformation during trophoblastic differentiation.     

DEVELOPMENTAL REGULATION OF TISSUE TRANSGLUTAMINASE DURING HUMAN PLACENTATION AND EXPRESSION IN NEOPLASTIC TROPHOBLAST

The expression of tissue transglutaminase (tTG) was studied during the formation of the normal human placenta and in molar pregnancies and choriocarcinoma, in order to correlate its expression with the functional characteristics of the recognized trophoblast cell types. tTG expression was found to be developmentally regulated. Before 6–7 weeks' gestation, only the chorionic villous cytotrophoblast expresses tTG. Thereafter the overlying syncytiotrophoblast becomes positive. tTG expression is gradually downregulated in the intermediate trophoblast cells emerging from the tips of the chorionic villi invading the uterine tissue. In the decidual wall, the intermediate trophoblast does not express tTG, whereas scattered syncytial cells, the placental bed giant cells, express tTG. Villi from complete hydatidiform mole (CHM) show tTG expression in both the cyto- and the syncytiotrophoblast. The intermediate trophoblast cells from CHM show heterogeneous tTG expression, with a majority of negative cells, whereas extravillous syncytia always express tTG. In choriocarcinoma, the tumour cells show heterogeneous tTG expression, with a majority of positive cells. Analysis of tTG protein and mRNA in placental extracts by Western and Northern blotting did not provide evidence for expression of the truncated form of tTG found in some cell types. The regulated expression of tTG in the normal placenta suggests that the enzyme is involved in important trophoblastic functions and may participate in the control of invasion. © 1997 by John Wiley & Sons, Ltd.     

中间型滋养细胞肿瘤的临床病理分析

目的探讨中间型滋养细胞（IT）源性肿瘤即胎盘部位滋养叶细胞肿瘤（PSTT）及上皮样滋养细胞肿瘤（ETT）临床病理特征及免疫表型表达特点、诊断与预后。方法北京妇产医院1959-2005年中,因恶性滋养叶疾病住院治疗患者共1012例,从中筛选6例PSTT及1例ETT,对其临床特征、病理诊断要点及免疫组织化学（SP法）结果进行分析,抗体包括CK18、胎盘催乳素（hPL）、人绒毛膜促性腺激素（hCG）、Mel—CAM（CDl46）及胎盘碱性磷酸酶（PLAP）。对照组为20例附有底蜕膜的早期绒毛及20例见有着床部位反应的葡萄胎。结果平均年龄PSTT为32．4岁,ETT为36岁;症状主要为阴道不规则出血和闭经;术前检查hCG呈正常→轻度→中度增高趋势,1例睾酮明显增高。5例PSTT术前行刮宫及宫腔镜切取标本之确诊率为3／5。镜下PSTT瘤细胞呈单个、条索状或片状浸润于肌纤维间,将单个或一束肌纤维分离;ETT则显示岛屿状细胞群位于玻璃样物及坏死物中,呈地图样结构。治疗手段以子宫切除术或术后辅以化疗为主。随访时间14个月至19年,其中1例PSTT术后5个月发生胰腺转移,单纯化疗PSTT患者疗效尚不能肯定,其余均无复发。结论PSTT与ETT分别为发生于着床部位IT及绒毛膜类型IT,二者有不同病理形态学,免疫组织化学特征性表达可辅助诊断和鉴别诊断;术前诊断性刮宫病理诊断具有重要临床意义;PSTT与ETT显示相同的生物学行为和预后。     

Antiphospholipid antibodies internalised by human syncytiotrophoblast cause aberrant cell death and the release of necrotic trophoblast debris

Antiphospholipid antibodies (aPL) are the strongest maternal risk factor for pre-eclampsia, a hypertensive disease of human pregnancy. Pre-eclampsia is triggered by a toxic factor released from the placenta that activates the maternal endothelium. Antiphospholipid antibodies cause the release of necrotic trophoblast debris from the placental syncytiotrophoblast and this debris can activate endothelial cells. In this study, we investigated how aPL affects syncytiotrophoblast death and production of necrotic trophoblast debris by examining the interaction between aPL and human first trimester placental explants. Human polyclonal and murine monoclonal aPL, but not control antibodies, were rapidly internalised by the syncytiotrophoblast. Inhibitors of endocytosis or the low-density lipoprotein receptor (LDLR) family, but not toll-like receptors, decreased the internalisation of aPL and prevented the release of necrotic trophoblast debris from the syncytiotrophoblast. Once internalised, aPL increased inner mitochondrial membrane leak and Cytochrome c release while depressing oxidative flux through Complex IV of the electron transport system in syncytiotrophoblast mitochondria. These data suggest that the human syncytiotrophoblast internalises aPL by antigen-dependent endocytosis involving LDLR family members. Once internalised by the syncytiotrophoblast, aPL affects the death-regulating mitochondria, causing extrusion of necrotic trophoblast debris which can activate maternal endothelial cells thereby contributing to the pathogenesis of pre-eclampsia.     

Intraplacental choriocarcinoma with fetomaternal transfusion

Intraplacental choriocarcinoma is very rare, and is usually found only after maternal and fetal metastatic disease is identified. The purpose of this case report is to review the incidence and findings of intraplacental choriocarcinoma. A term placenta was investigated because the newborn was born with severe anemia (Hb 3.0 g/dL). A 2 cm nodule was noted on the surface of the amniotic membrane and grossly resembled an infarction. The tumor was examined microscopically with immunohistochemical staining for the alpha- and beta-human chorionic gonadotropin (alpha-hCG, beta-hCG) subunits, human placental lactogen (hPL) and Ki-67. Microscopically, the tumor consisted of necrotic areas with proliferation of atypical trophoblastic cells and destruction of the villi and capillaries. The cells were positive for the alpha-hCG, beta-hCG subunits, hPL and Ki-67, consistent with intraplacental choriocarcinoma. The mother and newborn were investigated for the presence of metastatic disease. Computed tomography scans and magnetic resonance imaging of the mother and infant were negative for metastatic disease. Choriocarcinoma, limited only to the placenta with no evidence of metastatic disease is very rare. Primary intraplacental choriocarcinoma may frequently be overlooked or missed, and choriocarcinoma may possibly arise in the placenta more often than in retained or persistent trophoblast following pregnancy.     

Implantation site in normal pregnancy. A study with monoclonal antibodies.

In the present study, the presence of major histocompatibility complex antigens (MHC) and the degree and nature of inflammatory response in the human placenta were determined by staining frozen tissue sections with monoclonal antibodies and an immunoperoxidase technique. Although class I (HLA-A, B, and C) and Class II (HLA-DR, Ia-like) MHC antigens were not demonstrated in the syncytiotrophoblast, Class I antigens were found in trophoblast of the placental septum, shell, and implantation site and in the chorionic villous stroma. There was no staining for Ia-like antigens in the fetal components of the placenta. T cells were scarce and evenly scattered in the normal implantation site. No T cells infiltrated the chorionic villi. B cells and natural killer cells were not identified in the human placenta. Macrophages constituted more than 20% of the decidual cells and had morphologic features identical to those of "small decidual cells." The lack of T-cell infiltration of the fetal placental structures and their scarcity in the implantation site support the notion that T-cell-mediated immune response against placental antigens is not generated by the maternal host in normal pregnancy. The abundance of macrophages at the implantation site may be related to their possible role in the suppression of immune response.     

超常胎盘部位的病理形态与免疫组化研究

目的：探讨超常胎盘部位（ＥＰＳ） 的病理形态与免疫组化特征,提出鉴别诊断要点。方法：对１７ 例经病理检查诊断为ＥＰＳ的病例进行病理学形态观察,采用免疫组化方法标记滋养细胞ＨＣＧ、ＨＰＬ、ＥＭＡ、ＰＲＬ、ＰＬＡＰ、Ｖｉｍ 、ａｃｔｉｎ、ｃｅｒｂＢ２ 和ｃｍｙｃ。结果：ＥＰＳ组织学特征为以中间型为主的滋养细胞向蜕膜及平滑肌浸润,不破坏原有组织结构,并保留部分胎盘床特点。免疫组化标记ＨＰＬ、ＥＭＡ呈阳性或强阳性,ＨＣＧ多为弱阳性,其他多为阴性。结论：ＥＰＳ属于中间型滋养细胞为主的妊娠滋养细胞疾病。鉴别诊断应结合组织学、免疫组化及临床表现综合判断。     

胎盘部位过度反应及胎盘部位结节的临床病理分析

目的探讨胎盘部位过度反应及胎盘部位结节的临床病理学特征以及免疫组织化学染色在鉴别诊断中的意义。方法对15例胎盘部位过度反应及4例胎盘部位结节的临床及病理表现进行回顾性研究,并应用人绒毛膜促性腺激素(hCG)、人胎盘催乳素(hPL)、细胞角蛋白(CK)18、胎盘碱性磷酸酶(PLAP)、α-抑制素(inhibin),进行免疫组织化学染色。结果15例胎盘部位过度反应患者的年龄为25～40岁(平均31．5岁),4例胎盘部位结节患者年龄为26～39岁(平均34．3岁)。15例胎盘部位过度反应的组织学特征为：在子宫内膜、子宫肌层及螺旋动脉中有索条状及片状种植部位中间滋养细胞浸润,子宫内膜及肌层的结构没有破坏。4例胎盘部位结节在子宫内膜组织及变性坏死的绒毛间有多个以致密的嗜酸性玻璃样物质为背景的结节性病变,结节内为绒毛膜型中间滋养细胞。15例胎盘部位过度反应对hPL及CK18均呈阳性反应;4例胎盘部位结节均对CK18、α-抑制素及PLAP均呈阳性反应。所有15例胎盘部位过度反应Ki-67增生指数均≤5％。4例胎盘部位结节Ki-67增生指数均为0。结论胎盘部位过度反应及胎盘部位结节的临床及病理形态学特征不同于滋养细胞肿瘤。免疫组织化学染色对鉴别诊断有帮助。     

Expression of merosin, a tissue-specific basement membrane protein, in the intermediate trophoblast cells of choriocarcinoma and placenta

Merosin is a novel tissue-specific basement membrane-associated protein found in basement membranes of trophoblast, striated muscle and Schwann cells. In placental extracts, the immuno-reactivity for merosin was detected in a protein band of 80 kilodaltons, and a 65 kilodalton polypeptide fragment of merosin could be isolated from proteolytic digests of placenta. In the present study, we describe the expression of merosin in human choriocarcinomas and normal placentas using immunoperoxidase staining of paraffin-embedded tissues. All five choriocarcinomas studied show immunoreactivity for merosin. Tumor cells, exhibiting the morphology typical of the intermediate trophoblast, stained distinctly for merosin. The cytotrophoblast and syncytiotrophoblast cells in these tumors showed negligible or no staining. In second and third trimester human placentas, merosin immunoreactivity was found in large extravillar mononuclear trophoblast cells of the basal plate as well as in the trophoblast basement membranes of the chorionic villi. The results indicate that merosin is mainly expressed in the intermediate trophoblast cells of both neoplastic and normal origin, whereas almost no expression is seen in cytotrophoblast and syncytiotrophoblast. Consequently, it is suggested that the intermediate trophoblast may represent a third, independently differentiated trophoblastic cell type.     

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.