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C A Labarrere

Publications and source records attributed to C A Labarrere.

At least 19 recordsLinked to original sources
PubMed1992

Glycosylation of membrane cofactor protein (CD46) in human trophoblast, kidney and platelets.

Many cell surface glycoconjugates are differentiation markers and are involved in cell-cell and intermolecular interactions in development, immunity and cancer. Membrane cofactor protein (MCP) comprises structurally related 65 and 55 kDa glycoproteins that bear O- and N-linked glycans. MCP prevents amplification of autologous complement action on human cells. We used immunoblotting with MCP-specific monoclonal antibody TRA-2-10 to determine lectin-binding properties and glycosidase sensitivities of MCP in a study of cell-specific variation in glycosylation of this protein. The results showed that N-linked glycans on placental syncytiotrophoblast and cytotrophoblast, kidney and platelet MCP are similar in binding to concanavalin A and Lens culinaris lectins, but are not bound by leucophytohemagglutinin. Lectin binding prior to and after neuraminidase digestion indicates that MCP from these sources is highly sialylated. 65 kDa MCP was confirmed to contain more O-linked glycans than 55 kDa MCP. A fraction of platelet 65 kDa MCP is distinct, however, in bearing peripheral fucose residues. Syncytiotrophoblast is unique in containing a 110 kDa form of MCP in non-reducing SDS-PAGE that resembles 65 kDa MCP in glycosylation. Chorion laeve MCP in 4 of 8 preparations was unusually heterogeneous and differed from syncytiotrophoblast MCP after neuraminidase digestion in the forms bound to peanut agglutinin and WGA. The results indicated for the first time, differences in O-linked glycosylation of MCP in chorion laeve cytotrophoblast relative to syncytiotrophoblast, platelet and kidney MCP. We conclude that structures of MCP glycans can differ between trophoblasts and other cell types.

Antigens, CD↗
PubMed1992

The endothelial heparan sulfate-antithrombin III natural anticoagulant pathway in normal and transplanted human kidneys.

This is the first study of the antithrombin III-heparan sulfate natural anticoagulant pathway in human kidneys. Immunocytochemical experiments were done to demonstrate the pathway on normal renal endothelial cells. Enzymatic studies were done to show that the antithrombin III was anchored to endothelium by molecules of heparan sulfate. Displacement studies were done with glycosaminoglycans to show that the antithrombin III was bound to its glycosaminoglycan anchor via a heparinlike binding site, and replacement studies showed that antithrombin III could be returned to the same endothelial cells from which it was displaced. Immunocytochemical studies of biopsies showed that normally functioning renal allografts manifested the endothelial antithrombin III-heparan sulfate anticoagulant pathway. The pathway was compromised or absent from the microcirculation of biopsies from rejecting or rejected renal allografts, and the diminishment of endothelial ATIII was associated with the presence of fibrin deposition. It is concluded that compromise of the antithrombin III-heparan sulfate natural anticoagulant pathway results in compromised renal function in transplanted kidneys.

Adolescent↗
PubMed1992

Tissue factor in normal and transplanted human kidneys.

Tissue factor (TF) plays a central role in the initiation of blood coagulation that frequently is enhanced in renal allografts. The identification and localization of TF was studied immunocytochemically in biopsies from normal and transplanted human kidneys and classified according to its distribution. The clinical status of each allograft was then correlated with the TF classifications. From these correlations, four distributional types of TF were identified. In normal kidneys, TF was localized to glomerular epithelium and basement membranes. Glomerular TF expression did not colocalize with mesangial or endothelial HLA-DR reactivity as determined by double antibody techniques. Tissue factor in donor kidneys also was identified in the renal capsule and in the adventitia of large arteries. These structures were not reactive in long-term transplanted grafts. Some cadaver kidneys prepared for transplantation had depleted glomerular TF, and exhibited TF reactivity within stromal tissues. Long-term allografts with progressive loss of renal function and kidneys with advanced rejection exhibited diminished TF reactivity of glomerular epithelium and basement membranes. This was frequently associated with fibrin deposition within the glomeruli and in the intertubular microcirculation. These findings indicate that the evaluation of TF in transplanted kidneys is related to the prognosis of graft survival.

Adult↗
PubMed1992

Novel immunohistochemical markers of human renal allograft dysfunction--antithrombin III, Thy-1, urokinase, and alpha-smooth muscle actin.

We have studied the expression of alpha-smooth muscle actin (alpha sm-1) by mesangial cells, and the expression of Thy-1 glycoprotein, antithrombin III (ATIII), and urokinase by tubular epithelial cells in normal kidneys and dysfunctional renal allografts. Kidney biopsies were studied immunocytochemically for changes in each of these markers and the findings were classified into two groups and compared with creatinine plasma levels at the time the biopsies were taken. In dysfunctional grafts, mesangial alpha sm-1 and tubular epithelial Thy-1 reactivities were greatly diminished, and urokinase and ATIII were missing from proximal renal tubular epithelial cells. Urokinase, which was absent from normal renal glomeruli, appeared in glomeruli of some dysfunctional allografts. The possible usefulness of these markers in patient evaluations was supported by our finding that the distribution of vinculin, fibronectin, myosin, actin B4, desmin, glomerular HLA-DR, and the tubular expression of CD15 remained unchanged. These data prompt us to suggest that the immunocytochemical localization and evaluation of alpha sm-1, Thy-1, ATIII, and urokinase in kidney allografts may be useful adjuncts in the assessment of function in renal allografts.

Actins↗
PubMed1992

Vascular immunopathology and atheroma development in human allografted organs.

Human atherosclerosis requires decades to develop spontaneously, and its development customarily is not monitored by serial biopsies. Atherosclerosis in allografts develops within months, and biopsy specimens are usually obtained from the grafts. We have used immunocytochemical techniques to study biopsy specimens of cardiac and renal allografts for parameters of vascular changes. The antibodies used in this investigation were specific for T lymphocytes, macrophages, IgM, and complement, and detailed studies were done with the use of antibodies specific for components of the hemostatic, fibrinolytic, and natural anticoagulant pathways. The results indicated a lack of association between the appearance of cellular infiltrates and measurable alterations in vascular endothelium and smooth-muscle cells. Although infiltrating macrophages and lymphocytes were identified in biopsy specimens with vascular change, such changes were also observed in biopsy specimens that were devoid of cellular infiltrates. The most prominent vascular changes in endothelium and smooth-muscle cells were accelerated hemostasis, depressed fibrinolysis, and deranged anticoagulant pathways. A negative association between the presence of IgM and fibrin on endothelial cells was also identified. Whether vascular changes are due to immunologically mediated reactions or to as yet undefined metabolic stresses of the graft-host relationship remains to be determined. This study provides a model for the study of vascular changes in atheroma development as viewed through the window of transplant-induced atherosclerosis.

Arteriosclerosis↗
PubMed1991

A vitronectin-receptor-related molecule in human placental brush border membranes.

The heterodimeric vitronectin receptor (VNR) and platelet glycoprotein IIb/IIIa (GPIIb/IIIa) are two members of the integrin family of cell adhesion receptors that share the same beta subunit (GPIIIa). These proteins are involved in binding to vitronectin, fibrinogen and fibronectin and in cytoskeleton-membrane interactions. The present study shows that the human placental syncytiotrophoblast brush border membrane contains a heterodimer of subunit Mr values of 140,000 and 90,000 (non-reduced) or 125,000 and 100,000 (reduced). This protein was recognized by a monoclonal antibody to GPIIIa, rabbit antisera to the VNR and a human alloantiserum to GPIIIa. Brush border VNR-related protein bound to an immobilized peptide containing the Arg-Gly-Asp sequence and, less avidly, to immobilized fibrinogen. Only a small fraction of brush border VNR was associated with a cytoskeleton fraction. Membrane-bound brush border GPIIIa was distinct from that of platelets in its resistance to digestion by trypsin and Staphylococcus aureus V8 protease, and had a slightly lower mobility on SDS/PAGE. In addition, lectin-binding studies indicate glycosylation differences between microvillar and platelet GPIIIa heterodimers. Thus, although placental syncytiotrophoblast expresses a beta 3 integrin in its apical brush border, differences in protease sensitivity and carbohydrate content suggest that it may lack or mask certain antigenic determinants. This may be beneficial in avoiding harmful maternal alloantibody responses during pregnancy. Immunohistology showed that the VNR was present in syncytiotrophoblast apical but not basal plasma membranes, and was absent from other forms of trophoblast. The brush border VNR could function in localizing Arg-Gly-Asp-sequence-containing plasma proteins to the materno-trophoblastic interface.

Blood Platelets↗
PubMed1991

Factor VIII procoagulant: a marker of fibrinoid necrosis in normal term human placentae.

Factor VIII procoagulant (FVIIIPC) is a plasma glycoprotein cofactor for activated factor IX that activates factor X in prothrombin convertase and results in fibrin deposition. We have studied 50 normal term placentae for the presence of FVIIIPC, and found it in granular deposits almost exclusively in areas of fibrinoid necrosis. This observation was made in all fibrinoid areas. These deposits were associated with specific factors of the coagulation, anticoagulation and fibrinolytic pathways. These findings suggest coagulation and fibrinolysis are activated in areas of fibrinoid necrosis and indicate FVIIIPC is a marker of these areas.

Biomarkers↗
PubMed1991

Tissue factor in chronic villitis of unestablished etiology.

We have previously reported the presence in normal human placentae of coagulation, macrophages and helper T lymphocytes in inflammatory foci known as villitis of unestablished etiology. In order to investigate the link between coagulation and immunity, we have studied fetal stem vessel endothelium for tissue factor, which is made available by cytokines and activates coagulation via the extrinsic pathway. We found that fetal stem vessel endothelial cells of normal chorionic villi did not react with antibody to tissue factor. Normal placentae contain small numbers of villitis areas and endothelium in these areas was reactive with antibody to tissue factor. Endothelial tissue factor reactivity was more prominent in placentae from secondary recurrent spontaneous aborters and these placentae have greatly increased numbers of villitis areas. The tissue factor availability on fetal stem vessel endothelium may result from immunologically mediated cytokine release. The net effect of these reactions is the presence of lymphocytes, macrophages, coagulation, necrosis and vasculitis in villitis.

Abortion, Habitual↗
PubMed1991

HIV proteins in normal human placentae.

Cryostat sections of human normal term placentae were studied for evidence of immunopathology by using antibodies to lymphocytes, macrophages, platelets, and coagulation factors. Areas of so-called chronic villitis of unestablished etiology were identified in all placentae. The same tissues were examined for HIV protein antigens gp120, p17, p24, and gp41. No evidence for gp41 was found. Antigens gp120 and p17 were identified in normal chorionic villi in vimentin-positive fibroblast-like cells and in endothelium, respectively. Antigen p24 was localized to HLA-DR positive cells that morphologically resembled macrophages in areas of villitis. The distribution of gp120 and p17 was similar to that observed for tissue factor. These findings prompted speculation that retroviral proto-oncogenes that are known to encode for certain placental receptors could be involved in the presentation of tissue factor, and that gp120 may be a hitherto unrecognized immunobiological mechanism for the blockade of CD4 on maternal lymphocytes if and when such cells gain entrance to chorionic villi.

Chorionic Villi↗
PubMed1991

Cytoskeletal proteins in chronic villitis of unestablished etiology.

Cytoskeletal proteins (i.e., cytokeratins, vimentin, actin, and desmin) are normally present in the placental chorionic villi and are related to the maintenance of the villous shape, and to the ability of the villi to contract and permit a normal blood flow. In areas of villitis of unestablished etiology, the normal reactivity of these proteins in the villous core around fetal stem vessels disappears, and an increased number of cytokeratin positive cells is identified. The vascular damage in stem villi with villitis could develop ischemia in the villous tree promoting cytotrophoblast proliferation. Increased numbers of these areas could be related with the appearance of abnormal pregnancies.

Chorionic Villi↗
PubMed1990

Tissue factor: identification and characterization of cell types in human placentae.

This is an immunohistologic study of tissue factor (TF) in snap frozen, unfixed, human normal-term placentae. Antibodies to TF were a monoclonal to human brain TF purified on a factor VII-agarose affinity column, and a polyclonal to a synthetic polypeptide representing the carboxyl-terminal nine amino acids of human TF. The results detail the localization and distribution of TF and characterize the cells in which it is found. TF was not observed in trophoblast, trophoblastic basement membranes, or noncellular components of connective tissue. TF was identified in some but not all macrophages, most fibroblast-like cells, and occasionally in perivascular cells and endothelium. The most consistent and intense reactions were obtained with vimentin-positive fibroblast-like cells in loose connective tissue. TF usually was not identified in fetal stem vessel endothelial cells, but TF reactivity was found in some of these cells in chorionic villi with histologic evidence of chronic inflammation. Such areas are uncommonly found in normal-term placentae. The vast majority of TF-reactive cells did not react with antibody to factor VII and were not in contact with blood. The biologic purpose of producing relatively great amounts of TF in areas remote from circulating factor VII is not known.

Antibodies, Monoclonal↗
PubMed1990

Immunohistologic evidence that villitis in human normal term placentas is an immunologic lesion.

Villitis of unestablished origin is a lesion in placentas from normal and high-risk pregnancies. We have studied villitis areas in 25 normal term placentas for immune cells, coagulation components, and endothelial markers. Villitis areas were filled with activated (HLA-DR, HLA-DP, and HLA-DQ reactive) macrophages. B lymphocytes were not identified, and T lymphocytes were of the helper (CD4) phenotype. Antibodies to coagulation components revealed perivascular and trophoblastic basement membrane deposits of factor IX, increased numbers of platelets, and fetal stem vessels that did not react with endothelial markers. These findings suggest helper T lymphocytes activate macrophages that mediate coagulation activation and alter endothelium. This combination of immunologic events results in tissue changes that are histologically diagnosed as villitis. It is not known what triggers these immunologic events, but the finding of villitis in normal placentas suggests the causative factor(s) is present in all pregnancies.

Adult↗
PubMed1990

MHC class II reactivity of human villous trophoblast in chronic inflammation of unestablished etiology.

Absence of class II MHC antigens from human syncytiotrophoblast is a common finding in normal-term placentae. Since chronic villitis of unestablished etiology is a placental lesion frequently found in normal and abnormal term placentae, and fetal stem vessels are MHC class II-positive in these lesions, we asked if syncytiotrophoblast in villitis is reactive for MHC class II antigens. We found segments of syncytiotrophoblast that were reactive for the MHC class II HLA-DR, DP, and DQ antigens in villitis areas of normal-term placentae and in placentae from women with a history of recurrent spontaneous abortions. This reactivity was not due to trophoblast replacement by activated macrophages, though the possibility of crossreactive antigens and binding of soluble MHC class II antigens by receptors developed in areas of villitis could not be excluded. MHC class II antigen expression on syncytiotrophoblast could be due to cytokine release from activated macrophages and helper T lymphocytes which we have previously described in areas of villitis of unestablished etiology.

Abortion, Habitual↗
PubMed1989

Villitis in normal term human placentae: frequency of the lesion determined by monoclonal antibody to HLA-DR antigen.

Chronic villitis is a placental lesion of unestablished etiology. It is characterized by destruction of chorionic villi with a mononuclear infiltrate and focal areas of fibrinoid necrosis. The lesion frequently is seen in normal placentae, yet more lesions have been reported in placentae from abnormal pregnancies. We measured the extent of villitis in 25 normal term placentae by using both light microscopy and immunocytology for class II (HLA-DR) antigens of the major histocompatibility complex. HLA-DR antigens were found to be characteristic of villitis areas. Normal placentae showed striking variations in the incidence of villitis, but these variations did not correlate with clinical outcome.

Adult↗