Differential expression of MHC class I antigens on the placenta of the rat. A mechanism for the survival of the fetal allograft.

In some mating combinations in rats, there is a maternal antibody response to the maternal antigenic components of the placenta without any previous immunization of the mother. The highest response occurs in the WF (u) female mated to the DA (a) male, and it is against a unique MHC-encoded class I antigen, the Pa antigen, and not against the major allele-specific transplantation antigen of the DA strain, RT1.Aa. The development of mAbs to the Pa and Aa antigens allowed us to localize these antigens on the placenta and to explore the reason for the differential antibody response to them using immunohistochemical and biochemical techniques. Both antibodies reacted with the WF X DA placenta and stained the endovascular and interstitial trophoblast of the decidua, the basal trophoblast, Reichert's membrane, and the yolk sac epithelium, but they did not stain the labyrinthine trophoblast. Blocking studies showed that each antibody reacted with a separate molecule in the placenta. Anti-class II mAbs reactive with the a or u haplotype did not stain the WF X DA, DA X DA, or WF X WF placenta; hence, there are no class II antigens in the placenta. Electron microscopic studies of the semiallogeneic WF X DA placenta using the immunogold technique with both single- and double-labeling showed that only the Pa antigen was expressed on the surface of the basal trophoblast, but that both the Pa and Aa antigens were in the cytoplasm of these cells; neither antigen was found in the labyrinthine trophoblast. By contrast, the placenta from the syngeneic DA X DA mating expressed both the Pa and Aa antigens on the surface of the basal trophoblast as well as in the cytoplasm; neither antigen was found in the labyrinthine trophoblast. These observations were quantified morphometrically using electron photomicrographs of single-labeled tissues. Both the Pa and Aa antigens isolated from the plasma membrane of lymphocytes have heavy chains of 46 kD, but those antigens isolated from the plasma membrane of basal trophoblast cells have heavy chains of 43 kD. Based on densitometric measurements of autoradiographs, the Pa/Aa ratio in the basal trophoblast membrane is 23.5, whereas it is 0.46 in lymphocyte membranes. These studies show that there is differential regulation of the expression of class I antigens on basal trophoblast cells in semiallogeneic pregnancies, but not in syngeneic pregnancies, such that the major allele-specific transplantation antigen is scarcely expressed on the surface of the basal trophoblast.(ABSTRACT TRUNCATED AT 400 WORDS)

Localization of the Pa antigen on the placenta of the rat.

A unique class I MHC antigen, the Pa antigen, is the major immunogenic molecule on the placenta of the rat. It carries only a widely shared public antigenic determinant, and it is located on the basal trophoblast.

A unique antigen, RT11, in the placenta of the rat.

In the course of exploring the antibody response in the unsensitized WF (u) female pregnant by a DA (a) male, we prepared a hybridoma that secreted an antibody (mAb 213) that was specific to the a haplotype but identified an antigen different from Pa. This antigen was designated RT11. It is present from the twelfth day of gestation on the collagen fibers of the placenta and of all organs in fetal and adult rats. It is particularly prominent on red blood cells; in the yolk sac epithelium; in the walls of the endodermal sinus, blood vessels and bronchioles; and in capsules and trabeculae. A very small amount is present on DA lymphocytes, since 17-20% of them react with mAb 213 by cytofluorimetry. The RT11 antigen is absent from the basal and labyrinthine trophoblast cells, from the parenchymal cells of all organs, and from T and B cells. This distribution pattern is completely different from that of the Aa and Pa antigens. Inhibition and absorption studies showed that RT11 is not an integral part of the collagen molecule. The SDS-PAGE analysis of the immunoprecipitates of RT11 from radioiodinated whole-membrane extracts of red blood cells and from the glycoprotein fraction thereof showed that it is an unglycosylated protein of molecular weight 29,000. The evidence to date suggests that RT11 is a blood group antigen. Studies on the genetic control of the expression of RT11 were undertaken to determine whether a gene linked to the MHC was involved and whether the control mechanism was unigenic or polygenic. Backcrosses generated using inbred strains--(DA x BN)F1 x DA-- and using complementary congenic strains--(DA.1N x BN.1A) F1 x BN.1A--showed that the expression of RT11 was under polygenic control, and that both an MHC-linked gene (1.2 cM from RT1.Aa) and genes not linked to the MHC are involved. By contrast, the expression of the Pa antigen is under the control of an MHC gene only.

Identification, cellular localization, isolation, and characterization of human Clara cell-specific 10 KD protein.

Human lung lavage proteins were fractionated by centrifugation and molecular sieving. An antiserum to the post-albumin fraction of the soluble proteins reacted with a 10 KD protein and this protein was isolated by conventional chromatography. The protein, which has a pI of 4.8, consists of two 5 KD polypeptides and is rich in glutamic acid, leucine, serine, and aspartic acid amino acids. The protein does not bind to concanavalin A, pancreatic elastase, leukocyte elastase, or trypsin, and lacks anti-protease activity. It constitutes about 0.15% of the soluble proteins in lung lavage. Antibodies to the 10 KD protein specifically and exclusively stain Clara cells in human, dog, and rat. Staining of granules of Clara cells was prominent in the distal bronchioles; however, the non-ciliated cells of respiratory bronchioles did not stain for the 10 KD protein. This 10 KD protein appears in fetal lungs at 21 weeks of gestation, and was present in about 10% of the primary pulmonary adenocarcinomas. As a specific marker for Clara cells, this protein could be useful in the study of development, regulation of secretion, and pathobiology of these cells.

A cluster of neonatal herpes simplex infections without mucocutaneous manifestations.

Three cases of neonatal disseminated herpes simplex virus (HSV) infection are reported. They were all due to different strains of HSV-1, according to restriction endonuclease studies, and they represent the first cluster of neonatal-HSV infection at Magee-Womens Hospital. The neonatal symptoms occurred early, suggesting intrauterine infection. None of the babies had mucocutaneous lesions, and the mothers were asymptomatic and had no history of previous genital HSV infection.

Electron microscopic localization of the Pa and RT1.Aa antigens on the placenta of the rat.

A major factor in the ability of the placenta to avoid allograft rejection is the differential expression of MHC class I antigens on its surface. Using monoclonal antibodies and the electron microscopic immunogold technique, we have demonstrated that only the pregnancy-associated (Pa) antigen, which carries a broadly shared antigenic determinant, is expressed on the placental surface in the rat, whereas the allele-specific classical transplantation antigens are not. Both types of antigens are, however, present in the cytoplasm of the basal trophoblast but completely absent from the labyrinthine trophoblast.

The immunohistochemical localization of pregnancy-specific beta 1-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.

Low incidence of positive amnionic fluid cultures in preterm labor at 27-32 weeks in the absence of clinical evidence of chorioamnionitis.

In order to determine the utility of amniocentesis for detecting subclinical chorioamnionitis in asymptomatic afebrile women in preterm labor with intact membranes, we enrolled 47 women between 27-32 weeks' gestation in a prospective study. After enrollment, 38 women fulfilled all clinical and laboratory criteria for the study; nine women were excluded because they had a leukocyte count exceeding 15,000/microL. None of the 38 asymptomatic afebrile women had a positive culture from the amnionic fluid for bacteria, fungi, Mycoplasma hominis, Ureaplasma urealyticum, Chlamydia trachomatis, or any viruses. Sepsis was not proved in any of the 38 infants delivered to these patients. There was a clear relationship between histologic evidence of chorioamnionitis and failure of tocolytic therapy. Fetal lung profiles were mature in 29% of the amnionic fluid samples from 30-32 weeks' gestation, but in none of the amnionic fluid samples before 30 weeks. Amniocentesis does not seem useful to detect chorioamnionitis in asymptomatic afebrile women with preterm labor and intact membranes at 27-32 weeks' gestation, and should be reserved for those cases in which information about fetal lung maturity would be helpful.

Ontogeny of expression of Pa and RT1.Aa antigens on rat placenta and on fetal tissues.

The unique pregnancy-associated (Pa) antigen, which is a class I antigen encoded by the major histocompatibility complex (MHC), elicits a nondestructive maternal antibody response. By contrast, the class I transplantation antigen RT1.Aa elicits a destructive antibody response in tissue transplantation but not during pregnancy. With the use of the avidin-biotin complex (ABC) immunohistochemical method, the Pa and RT1.Aa antigens were localized on the basophilic and giant cells of the basal zone trophoblast, the endovascular trophoblast and decidual interstitial trophoblast, and the chorioallantoic membrane but not on the labyrinthine zone trophoblast as early as the 12th day of gestation. These two antigens were also expressed on the epidermis, hair follicles, spleen, thymic medulla, bronchial epithelium, intestinal epithelium, the hepatic Kupffer cells, endocardium, endothelium of blood vessels, renal tubular cells and glomeruli, and renal pelvis and ureter of fetal and adult rat tissues. Absorption studies with placental tissue confirmed the presence of these two antigens in the rat placenta, and antibody-blocking studies confirmed their unique specificities.

Neonates with electrically confirmed seizures and possible placental associations.

Placental specimens were reviewed from 73 singleton pregnancies of women whose offspring received electroencephalogram (EEG) studies in the neonate period. A group of 43 neonates (postconception age [PCA] 23-44 weeks) with electrically confirmed seizures in the immediate neonate period were compared with 30 healthy preterm and term infants of comparable PCA who had no electrographic seizures. Pathologic placental changes were separated: Group A consisted of chorioamnionitis, edema, meconium staining, and/or retroplacental hematoma. Group B consisted of abnormal villous maturation, infarction, and/or chronic villitis. Logistic regression analyses calculated the odds ratio of having Group A or Group B placental lesions in each neonate group as a function of increasing PCA. For the seizure group, the odds of having Group B with or without Group A placental lesions increased by a factor of 1.2 for each postconception week up to 43 weeks PCA. For a 15-week interval the odds of having Group B lesions for the seizure group increased by a factor of 12.1 (P < 0.007). Ratios were not significant for Group A lesions alone in the seizure group or for either Group B or Group A findings in the neonate group without seizures. Pathophysiologic events in utero leading to Group B rather than Group A findings are associated with electrically confirmed seizures in near-term and term infants. Group A lesions were considered more likely to have intrapartum or peripartum associations, whereas Group B lesions were considered more likely to have antepartum associations.

Estimation of hepatic hematopoiesis in second and third trimester singleton gestations using flow cytometric light scatter analysis of archival autopsy tissue.

The purpose of this investigation was to develop a simple, quantitative, reproducible and objective method for estimating fetal hepatic hematopoiesis using flow cytometric light scatter measurements and to use this methodology to determine standard values for singleton gestations. Percent hepatic hematopoiesis was estimated from autopsy tissue both flow cytometrically using forward angle and side light scatter characteristics and histologically (single observer) in 67 s and third trimester singleton gestations without evidence of infection, congenital malformation, chronic maternal or placental disorders, or growth retardation. Correlation of flow cytometric and histologic estimates was 0.70 with flow cytometric estimates showing less variability than histologic estimates, especially during the second trimester. Flow cytometric estimates of hepatic hematopoiesis were relatively constant at 50-70% between 16 and 27 weeks gestational age and decreased during the third trimester to a level of approximately 25-30% at term. These results confirm and quantitate the predicted decrease in hepatic hematopoiesis between the second and third trimesters of gestation as well as its persistence at term. In addition, they demonstrate that flow cytometric light scatter analysis is an objective, valid and simple method for estimating hepatic hematopoiesis in archival autopsy tissue and provides objective standard values for comparison with estimates in pathologic gestations.

Sirenomelia. Angiographic demonstration of vascular anomalies.

A 1,730-g infant with severe caudal regression syndrome (sirenomelia) died shortly after delivery, after a 34-week gestation. Autopsy findings included multiple skeletal anomalies, renal agenesis, amnion nodosum, and a single lower extremity. Postmortem arteriography demonstrated a persistent vitelline artery and documented the vascular pattern within the lower extremity. To our knowledge, angiographic demonstration of the lower limb vascularity has not been described previously in sirenomelia. The angiographic findings support the pathogenetic concept of limb bud fusion and malrotation of the limb in sirenomelia after damage to the posterior axis mesoderm in early embryonic life. Postmortem arteriography is an inexpensive, retrievable, and easy means of documenting vascular anomalies in the fetus or infant with multiple congenital abnormalities.

Thyroid-gland plasma cell neoplasm (plasmacytoma).

A 61-year-old man with a primary thyroid plasmacytoma was studied. Intracytoplasmic monoclonal immunoglobulin (IgG-kappa) was demonstrated in tissue sections, using the immunoperoxidase technique. After histologic diagnosis of plasmacytoma, serum immunoelectrophoresis revealed a monoclonal component (IgG-kappa). Roentgenographic skeletal survey and bone marrow examination gave normal results. The patient received postoperative therapy with radiation and drugs. As of this writing, he is alive 20 months after diagnosis, without evidence of tumor.

Unusual presentations of fetal teratoma.

Teratomas are the most common congenital neoplasm. Fetal intracranial teratomas generally are large solid/cystic tumors that often completely replace normal brain tissue. Mediastinal teratomas are uncommon and rarely result in nonimmune hydrops fetalis. We describe two unusual presentations of fetal teratoma. The first is a fetus with massive hydrocephalus and marked facial deformities that were caused by a small intracranial teratoma. The second is a fetus with a mediastinal teratoma associated with non-immune hydrops fetalis. In both cases, compression by the mass resulted in lethal sequelae.

Predicting in vitro tissue culture growth for cytogenetic evaluation of stillborn fetuses.

A prospective study was undertaken of 131 perinatal deaths to determine whether gestational age, body weight, maceration degree and autopsy interval influenced successful in vitro tissue culture for cytogenetic evaluation. Perinatal populations were categorized as neonatal death (NND), fresh stillbirth (FSB), or graded as macerated stillbirth (MAC-0, MAC-1, MAC-2, MAC-3). Metaphase production by at least 15 cells separated 'growth' from 'no growth' categories after sampling liver, kidney and spleen. Body weight and degree of maceration were predictive of successful 'growth', while gestational age and autopsy interval were not. Body weight was significant in separating 'growth' from 'no growth' in NND (P = 0.05), FSB, MAC-0 and MAC-1 (P = 0.01). Growth probabilities were 0.78 (NND), 0.57 (FSB), 0.49 (MAC-0), 0.38 (MAC-1) and zero for MAC-2 and MAC-3. We conclude that (a) tissues from MAC-2 and MAC-3 fetuses do not grow and thus need not be sampled at autopsy, (b) maceration degree and body weight can be used to predict the growth probability in the other categories, (c) tissue samples can be taken during daylight hours, since autopsy interval does not influence successful growth provided the fetus is refrigerated at 4 degrees C, (d) all of the above conclusions have cost-efficiency implications for cytogenetic laboratories.

A retrospective study of maternal deaths in the Zimbabwean black.

PIP: The record charts of all female deaths 14 to 55 years of age inclusive at the Harare Hospital were retrospectively reviewed for the 2 year period January 1, 1972 to December 31, 1973. The patients were divided into an obstetric group (above 20 completed weeks of gestation) and an abortion group (below 20 completed weeks of gestation). The causes of death and maternal mortality rate were compared with those of England and Wales for the same period. There were 73 deaths, with obstetric death accounting for 53 (72.6%) and abortion for 20 (27.4%). Of 56 (76.7%) pregnancy-related deaths, 39 (69.6%) were in the obstetric and 17 (30.4%) in the abortion groups. Maternal mortality rate was 1.70 per 1000 total births. 57 of 73 deaths occurred within 40 days of delivery. 49 (57.5%) patients were para 4 and less while 30 (42.3%) were para 5 or more. 53 (72.6%) patients were 30 years of age or less. Sepsis was a major cause of death. Pulmonary embolism was not found in any patient. The maternal mortality rate of Black Zimbabweans is 10 times higher than that for England and Wales (0.16/1000 total births) but similar to that for South Africa (1.40 per 1000 births). The difference in mortality rates between this study and that for England and Wales is probably socioeconomic with its associated high patient-doctor ratio, distance of patients from adequate medical services, transportation and lack of population sensitivity to obstetrical preventive practice. Patient delay in seeking obstetrical care was a major avoidable factor in pregnancy-related deaths. This problem of patient delay may be eliminated through ensuring availability of enough municipal clinics, transportation, obstetric education, and improved social status. Surgical errors by registrars in training and errors of clinical judgment during a period when patient/staff ratio was excessively high also contributed to the deaths. An acceptable patient/staff ratio and accurate documentation of maternal deaths should be maintained.^ieng