Chronic villitis of unknown etiology and massive chronic intervillositis have similar immune cell composition

INTRODUCTION

Chronic villitis of unknown etiology (CVUE) and massive chronic intervillositis (MCI) are placental lesions associated with infiltration of mononuclear cells in the chorionic villi and the intervillous spaces, respectively. It is not well known whether immune cells in CVUE and MCI have similar phenotypic characteristics.

METHODS

A cross-sectional study of third trimester placentas was conducted to identify immune cell subpopulations in CVUE and MCI (n = 17/group). CVUE was diagnosed with H&E staining and antibody to CD3 in serial sections; and MCI, by the presence of massive infiltration of mononuclear cells in the intervillous spaces. Immune cells, ICAM-1 expression and nuclear factor κB (NF-κB) activation were determined immunohistochemically.

RESULTS

CVUE and MCI showed similar infiltrates, mainly CD68+ and CD3+ cells. Most cells (>80%) were CD45RB+, and one third were CD45RO+ in both lesions. There were slightly more CD8+ than CD4+ cells in both CVUE and MCI. More than 90% of cells in CVUE and MCI were ICAM-1+ with NFκB nuclear localization. Syncytiotrophoblast ICAM-1 expression was significantly (p < 0.001) higher in MCI (mean of 81.0; range of 71.6-86.0) than in CVUE (52.4; 36.4-59.4) or normal placentas (0.2; 0.0-0.6). Both, failure of physiologic transformation of spiral arteries and placental atherosclerosis-like lesions of atherosis were significantly more frequent in MCI than in CVUE or normal placentas (p = 0.044 and p = 0.007, respectively).

DISCUSSION

These finding suggest that MCI and CVUE have very similar infiltration of immune cells although MCI has more severe placental lesions.

Early prediction of cardiac allograft vasculopathy and heart transplant failure

Early risk-prediction is essential to prevent cardiac allograft vasculopathy (CAV) and graft failure in heart transplant patients. We developed multivariate models to identify patients likely to experience CAV, severe CAV, and failure due to CAV, at 1, 5 and 10 years. A cohort of 172 patients was followed prospectively for 6.7 ± 3.9 years. Logistic regression models were developed and cross-validated using bootstrap resampling. Predictive markers of atherothrombosis (myocardial fibrin deposition, and loss of vascular antithrombin and tissue plasminogen activator) and arterial endothelial activation (intercellular adhesion molecule-1 expression) were measured in serial biopsies obtained within 3 months posttransplant. Most markers were univariately associated with outcome. Multivariate models showed that loss of tissue plasminogen activator was the dominant and, in most cases, only predictor of long-term CAV (p < 0.001), severe CAV (p < 0.001), and graft failure due to CAV (p < 0.001). The models discriminated patients having adverse outcomes, had particularly high negative predictive values (graft failure due to CAV: 99%, 99% and 95% at 1, 5 and 10 years) and predicted event incidence and time to event. Early absence of atherothrombotic risk identifies a patient subgroup that rarely develops CAV or graft failure, implying that this low-risk subgroup could possibly be followed with fewer invasive procedures.

Vascular anticoagulation and transplant coronary artery disease

Fibrin deposits are found in and around the vessels in transplant coronary artery disease, in spontaneous atherosclerosis, and in the microvasculature of failing cardiac allografts. Fibrin is deposited due to a failure in anticoagulant pathways, one of the most important being the heparan sulfate proteoglycan-antithrombin (AT) natural anticoagulant pathway. A failure in this pathway results in a loss of AT binding in veins and arteries and increased fibrin deposition. This is associated with an increased risk of coronary artery disease and graft failure. Recovery of the previously lost vascular AT binding is associated with the development of a novel binding of AT by capillaries. The development of capillary AT binding is associated with significantly less coronary artery disease and improved survival. Understanding the mechanisms involved in the development of this unusual binding of AT by capillaries is important in developing new treatments directed to promote microvascular AT binding and reduce the deposition of fibrin.

Pathologic markers of allograft arteriopathy: insight into the pathophysiology of cardiac allograft chronic rejection

Transplant-associated coronary artery disease (CAD) is the principal limiting factor for the long-term survival of heart transplant patients. This review discusses early risk factors for the subsequent development of transplant-associated CAD. Early risk factors associated with a prothrombogenic microvasculature, such as deposition of microvascular fibrin, depletion of vascular tissue plasminogen activator, presence of endothelial activation of the allograft arterial tree, and loss of vascular antithrombin, as well as changes in circulation (ie, detectable serum cardiac troponin I and elevated serum soluble intercellular adhesion molecule-1 levels) are presented and discussed. New therapies that could improve the status of the allograft microvasculature and may prevent or mitigate the development of transplant-associated CAD are considered.

Vascular antithrombin and clinical outcome in heart transplant patients

A procoagulant microvasculature is associated with accelerated development of coronary artery disease (CAD) and failure in heart transplant patients. This study was performed to evaluate how changes in natural anticoagulation within cardiac allografts affect outcome. We prospectively studied 141 consecutive cardiac allograft recipients who underwent transplantation between 1988 and 1997. Serial endomyocardial biopsy specimens (6.5 +/- 0.1 biopsy specimens/patient) obtained during the first 3 months after transplantation were studied immunohistochemically to evaluate vascular antithrombin, and annual coronary angiograms (3.8 +/- 0.2 angiograms/patient) were studied to evaluate CAD. Antithrombin was present in arteries and veins, but not in capillaries, of all donor heart biopsy samples. Allografts that maintained vascular antithrombin had the best prognosis. Allografts with early and persistent loss of vascular antithrombin (n = 21) developed CAD earlier (p < 0.001), developed more severe disease (p < 0.001), showed more disease progression (p < 0.001), and failed more often (p = 0.003) and earlier (p < 0.001) than allografts retaining normal vascular antithrombin (n = 45). However, allografts that lost and recovered vascular antithrombin while developing unusual capillary antithrombin binding (n = 75) had less CAD, developed CAD later, had less severe disease and less disease progression (p < 0.01), and failed less often (p = 0.01) and later (p = 0.03) than allografts with persistent loss of vascular antithrombin. The persistent lack of a thromboresistant microvasculature increases risk of subsequent CAD and graft failure. However, recovery of vascular antithrombin and development of unusual capillary antithrombin binding improves allograft outcome.

Increased vascular endothelial growth factor expression in human hearts with microvascular fibrin

We have shown that microvascular changes that promote fibrin deposition in human cardiac allografts adversely affect clinical outcome. However, some allografts exhibit phenotypic changes in capillaries following the deposition of fibrin, which subsequently provide a significant survival advantage. The mechanism(s) involved in these capillary changes is(are) unknown. Similarly, although we have shown a significant temporal relationship between microvascular fibrin deposition and vascular endothelial growth factor (VEGF) immunoreactivity in cardiac allografts, the cellular source and relative changes in VEGF gene expression under these conditions are not known. Using immunocytochemical techniques, biopsies devoid of fibrin deposition lacked detectable VEGF immunoreactivity, whereas biopsies with fibrin deposition showed VEGF immunoreactivity in cardiocytes, interstitium, and some microvessels. By in situ hybridization, biopsies without microvascular fibrin deposition showed faint VEGF hybridization signals confined primarily to cardiocytes. In biopsies with fibrin deposition, strong VEGF hybridization signals were detected in cardiocytes, arteriolar smooth muscle cells were occasionally labeled, and endothelial cells were rarely labeled. By quantitative RT-PCR, biopsies with fibrin deposition (n=5) relatively expressed approximately three-fold more VEGF mRNA than biopsies without fibrin deposition (n=5 P=0.02). Serum VEGF titers also were greater (P=0.01) in recipients with fibrin deposition (372.9+/-66.7 pg/ml n=18) compared to recipients without fibrin deposition (172.1+/-25.0 pg/ml n=16). Collectively, these results support the hypothesis that increased myocyte-derived VEGF production following microvascular fibrin deposition in transplanted human hearts may act in a paracrine manner to promote activational and phenotypic changes in capillaries that provide a survival advantage for the allografts.

Value of serum-soluble intercellular adhesion molecule-1 for the noninvasive risk assessment of transplant coronary artery disease, posttransplant ischemic events, and cardiac graft failure

BACKGROUND

Adhesion molecules on arterial endothelium have been implicated in spontaneous atherosclerosis and transplant coronary artery disease (CAD). We studied whether elevated serum-soluble intercellular adhesion molecule-1 (sICAM-1) during the immediate posttransplant period was a risk factor for CAD, posttransplant ischemic events, or cardiac graft failure.

METHODS AND RESULTS

We initially studied serum sICAM-1 in a subset of 16 cardiac allograft recipients (5.5+/-0.7 samples per patient) to determine a cutoff point that best correlated with presence of arterial and arteriolar endothelial ICAM-1 in matching endomyocardial biopsies. The cutoff value was 308 ng/mL. Subsequently, we prospectively evaluated serum sICAM-1 in serial samples (5.3+/-0.1 per patient) obtained during the first 3 months after transplantation in a validation subset of 130 recipients and correlated early sICAM-1 levels with long-term outcome. Serum sICAM-1 >308 ng/mL correlated significantly with ICAM-1 on arterial and arteriolar endothelium (P:=0.02). Cardiac allograft recipients with serum sICAM-1 >308 ng/mL had 2.67 (95% CI, 1.28 to 5.59, P:=0.009) times greater risk of CAD and 3.63 (95% CI, 1.05 to 12.5, P:=0.04) times greater risk of graft failure. Recipients with sICAM-1 >308 ng/mL also developed more severe CAD (P:=0.009) and more ischemic events (P:=0.03) after transplantation.

CONCLUSIONS

Serum sICAM-1 levels can be used to noninvasively assess risk of transplant CAD, posttransplant ischemic events, and cardiac graft failure.

Platelet cryopreservation using a combination of epinephrine and dimethyl sulfoxide as cryoprotectants

Current methods of platelet storage are unsatisfactory because of the short shelf life of platelets and the rapid loss of platelet viability. We have developed a cryopreservation method that results in less damage from freezing and higher recovered function of platelets. Platelets were cryopreserved using a combination of epinephrine (EPN) and dimethyl sulfoxide (Me(2)SO) as cryoprotectants. The response of platelets to agonists was studied by flow cytometry and aggregation tests. Cryopreserving platelets with Me(2)SO decreased platelet annexin V binding due to freezing. The combination of EPN with Me(2)SO enhanced Me(2)SO cryoprotection and decreased platelet microparticle generation, suggesting that cryopreserving platelets using this combination is associated with increased platelet integrity. Platelet cryopreservation with an Me(2)SO/EPN combination also increased platelet aggregability, which was demonstrated by decreasing the lag phase and increasing the aggregation density to 66.39% +/- 6.6 that of fresh platelet-rich plasmas. We conclude that adding EPN as a combined cryoprotectant improves the quality of Me(2)SO-frozen platelets. As a method of aggregation of cryopreserved platelets, this method is comparable to that of normal fresh platelets and may improve the conditions for platelet transfusion.

Cardiac-specific troponin I levels and risk of coronary artery disease and graft failure following heart transplantation

CONTEXT

Previous studies have yielded conflicting data regarding whether a relationship exists between elevated cardiac troponin levels and acute allograft rejection in patients who have received heart transplants.

OBJECTIVE

To determine whether cardiac troponin I levels after heart transplantation were associated with a procoagulant microvasculature and long-term allograft outcome.

DESIGN

Prospective cohort study with a mean (SE) follow-up of 45.1 (2.5) months. Serum troponin I levels were measured 9.9 (0.2) times per patient during the first 12 months after heart transplantation.

SETTING

Heart transplant center in the United States.

PATIENTS

A total of 110 consecutive patients who received a heart transplant between 1989 and 1997 and survived at least 1 year after transplantation.

MAIN OUTCOME MEASURES

Histological and immunohistochemical biopsy findings, development of coronary artery disease (CAD), and graft failure in patients with vs without elevated serum cardiac troponin I levels.

RESULTS

All recipients had elevated troponin I levels during the first month after transplantation. Troponin I levels remained persistently elevated during the first 12 months in 56 patients (51%) and became undetectable in 54 patients (49%). Persistently elevated troponin I levels were associated with increasing fibrin deposits in microvasculature and cardiomyocytes (P<.001). Patients with persistently elevated levels of troponin I had significantly increased risk for subsequent development of CAD (odds ratio [OR], 4. 3; 95% confidence interval [CI], 1.8-10.1; P<.001) and graft failure (OR, 3.4; 95% CI, 1.2-9.7; P =.02), and also developed more severe CAD (OR, 4.2; 95% CI, 1.9-9.3; P<.001) and showed more disease progression (OR, 3.7; 95% CI, 1.3-10.4; P =.009).

CONCLUSION

In this study, elevated cardiac troponin I levels, which are considered to be a noninvasive surrogate marker of a procoagulant microvasculature, identified a subgroup of patients with high risk for developing CAD and graft failure after cardiac transplantation. JAMA. 2000;284:457-464

Antibodies to endothelial cells identify myocardial damage and predict development of coronary artery disease in patients with transplanted hearts

BACKGROUND

Transplant-induced coronary artery disease is a leading cause of graft failure in cardiac allograft recipients after the first year of transplantation, but there presently is no test to identify patients at high risk for developing the disease. Our research is focused on development of a predictive test to identify patients at high risk of developing the disease.

METHODS

Sixty-eight cardiac allograft recipients transplanted and followed at Methodist Hospital between 1982 and 1996 were studied. Serial annual angiograms were used to diagnose coronary artery disease, and serial endomyocardial biopsies were used to detect cellular infiltrates and microvascular disease. Biopsy-matched serum samples were used for cardiac troponin-T determinations as measures of myocardial damage, and serum antibodies to endothelial cells were determined by using flow cytometry, enzyme-linked immunosorbent assay and immunoblotting techniques. The endothelial antibody data were evaluated statistically for associations with angiographic changes, biopsy findings and biochemical evidence of myocardial damage.

FINDINGS

Antibodies to endothelial cells were identified by all three techniques, and significant associations were found for the amount of antibody identified by Western immunoblotting with histological rejection grades in biopsies, which were confirmed immunocytochemically as macrophages (p<0.01) and T lymphocytes (P = 0.03). These antibodies also associated significantly with vascular antithrombin depletion (p = 0.02), biochemical evidence of myocardial damage (p = 0.005) and subsequent development of coronary artery disease (p = 0.03).

INTERPRETATION

The significant association of anti-endothelial antibodies with cellular infiltrates, depletion of vascular antithrombin and myocardial damage suggests a role for antibody in the development of transplant-induced arteriopathy. The significant association of antiendothelial antibodies with the future development of coronary artery disease further suggests that assessment of these antibodies may provide a non-invasive test to predict the development of transplant-induced coronary artery disease.

Immunohistochemical analysis of vascular prostheses implanted with the left ventricular assist system

BACKGROUND

Dacron vascular prostheses are associated with thromboembolic complications and inflammatory responses; impregnation with bovine collagen reportedly stimulates additional inflammatory/immunologic complications. The Novacor (Baxter Healthcare Corp., Oakland, CA, USA) left ventricular assist system uses Dacron inflow and collagen-impregnated Dacron outflow prostheses.

METHODS

Explanted inflow and outflow prostheses were evaluated for inflammatory/immunologic, hemostatic, anticoagulant, and fibrinolytic pathways. Non-implanted prostheses immersed in whole blood or plasma were used as controls.

RESULTS

Immunoglobulins and complement components were observed in all prostheses with activated macrophages being present only in implanted prostheses. Antithrombin III was observed in all prostheses whereas fibrin, tissue plasminogen activator, and alpha-2 plasmin inhibitor were present only in implanted prostheses. Endothelial and smooth muscle cells associated with vascular structures containing collagen type IV and laminin were observed solely in implanted prostheses.

CONCLUSION

An inflammatory response occurs and key components of hemostatic, anticoagulant, and fibrinolytic pathways are present within implanted prostheses. These processes are accompanied by endothelial and smooth muscle cell infiltration which appear to lay the foundation for neovessel development.

Unique epitopes of lactoferrin expressed in human cytotrophoblasts involved in immunologic reactions

OBJECTIVE

Lactoferrin is an iron-binding protein that has been implicated in protection against infections and allogeneic recognition reactions and in the control of cell growth. We studied the biochemical characteristics and expression of the unique lactoferrin epitopes (LF(1)) in human placentas.

STUDY DESIGN

Immunohistologic studies of normal human term placentas were done by using monoclonal antibodies to LF(1). Double-antibody experiments were done by using monoclonal antibodies to markers of inflammation (macrophages, human leukocyte antigen [HLA-DR]). LF(1) was studied immunochemically by using lactoferrin fragments produced by the reaction of lactoferrin with trypsin or N-glycanase.

RESULTS

Anti-LF(1) monoclonal antibodies reacted with most interstitial cytotrophoblasts in the basal plate and with villous cytotrophoblasts of some but not all chorionic villi. Cytotrophoblasts expressing LF(1) were associated with large numbers of HLA-DR-reactive macrophages. Anti-LF(1) monoclonal antibodies reacted with 2 distinct tryptic fragments of lactoferrin, and these reactivities were not affected by treatment with N-glycanase.

CONCLUSION

Placental cytotrophoblasts express unique epitopes of lactoferrin (LF(1)). Such expression is increased in the presence of activated macrophages. This expression could be an extraembryonic response to inflammation and maternal allogeneic recognition as an effort to protect trophoblastic cells. The LF(1) epitopes might represent conserved polypeptide epitopes on 2 homologous lobes of lactoferrin.

Localization and characterization of antithrombin in human kidneys

Antithrombin is a serine protease inhibitor that is critical in maintaining a thromboresistant vasculature. The association between low serum antithrombin concentration and renal disease suggests that the kidney plays a role in the conservation of plasma antithrombin. We used immunohistochemical techniques to determine the spatial distribution, heparin binding characteristics, and intracellular and intercellular localization of antithrombin in biopsy specimens (n = 53) of human donor kidneys obtained at the time of transplantation. In the renal cortex, double antibody techniques demonstrated the presence of intracellular antithrombin in proximal tubule epithelial cells. The reactivity was granular and was co-localized with vesicle-like structures. Distal and collecting tubules did not demonstrate intraepithelial antithrombin reactivity. No tubule structures in the medullary region demonstrated intracellular antithrombin, but all these structures showed intense basement membrane antithrombin reactivity. Double antibody techniques also demonstrated that the heparin binding domain of intraepithelial antithrombin was occupied. Semiquantitative scores for intraepithelial antithrombin were significantly decreased in renal biopsy specimens obtained 30 min after anastomosis compared with biopsies from the same organ obtained before anastomosis. These findings suggest that antithrombin, probably in association with heparin or heparan sulfate, is internalized by renal proximal epithelial cells. Although the ultimate fate of intraepithelial antithrombin is not known, this may represent a mechanism by which the kidney helps to maintain plasma antithrombin concentrations.

Relationship of fibrin deposition in microvasculature to outcomes in cardiac transplantation

The development of transplant coronary artery disease (CAD) is directly associated with outcome in cardiac transplantation. The relationship between microvascular fibrin deposition early after transplantation and subsequent development of transplant CAD is discussed in this article. In this article the presence of microvascular fibrin and its association with other prothrombogenic changes within the cardiac microvasculature, such as loss of vascular antithrombin, depletion of arteriolar tissue plasminogen activator, and presence of arterial and arteriolar endothelium activation, as well as changes in circulation associated with prothrombogenic changes that have predictive value for subsequent transplant outcome are presented and discussed. Novel therapeutic approaches that may prevent the development of transplant CAD and consequently affect outcome are considered.

Serum cardiac troponin-T concentrations predict development of coronary artery disease in heart transplant patients

BACKGROUND

Development of coronary artery disease in cardiac allograft recipients is the major cause of graft failure after the first year of transplantation. Unfortunately, there is no noninvasive method of identifying patients at greatest risk of developing this disease. We have asked whether serum concentrations of cardiac troponin-T predict development of coronary artery disease.

METHODS

Annual coronary angiograms, serial endomyocardial biopsies, and serum cardiac troponin-T concentrations were obtained from 68 cardiac transplant patients who were followed for 68.8+/-11.9 months after surgery. Troponin-T concentrations were measured by using an enzyme-linked immunosorbent assay, and biopsies were assessed histologically for rejection grades and immunohistochemically for cellular infiltrates, arteriolar endothelial activation, fibrin deposits, and vascular fibrinolytic and anticoagulant components.

RESULTS

Troponin-T values did not associate with demographic, clinical, or laboratory findings, but they significantly associated with arteriolar endothelial activation (P<0.001), fibrin deposition (P<0.001), depletion of vascular fibrinolytic (P=0.007) and anticoagulant components (P=0.02), and infiltration of macrophages (P <0.001) but not T lymphocytes (P=0.36). Troponin-T concentrations also significantly associated with future development of coronary artery disease (P<0.001). Patients with persistent troponin-T values of 0.10 ng/ml or greater were found to develop the disease within 8.7+/-2.1 months, whereas patients who had initial troponin-T values of 0.10 ng/ml or greater and subsequently fell and remained below 0.10 ng/ml did not develop coronary artery disease in 40 months.

CONCLUSIONS

Troponin-T concentrations significantly associated with macrophage infiltrates, microvascular fibrin deposits, arteriolar endothelial activation, depletion of vascular fibrinolytic and anticoagulant components, and the future development of coronary artery disease. The troponin-T assay is an outpatient procedure performed on small amounts of blood at little cost, risk, or inconvenience, and it appears to be the first biochemical predictor of transplant-induced coronary artery disease.

Expression of a novel high molecular-weight myosin light chain kinase in endothelium

Myosin light chain phosphorylation results in cellular contraction and is a critical component of agonist-mediated endothelial cell (EC) junctional gap formation and permeability. We have shown that this reaction is catalyzed by a novel high molecular-weight Ca2+/calmodulin-dependent nonmuscle myosin light chain kinase (MLCK) isoform recently cloned in human endothelium (Am. J. Respir. Cell Mol. Biol., 1997;16:489-494). To characterize EC MLCK expression further in cultured and adult tissues, we employed immunoblotting techniques and reverse transcriptase-polymerase chain reaction to demonstrate that freshly isolated and cultured human macro- and microvascular EC express only the EC MLCK isoform (214 kD), which is distinct from smooth-muscle MLCK isoforms (130 to 150 kD). Immunocytochemical studies demonstrated the presence of the high molecular-weight MLCK isoform in adult human cardiac endothelium using anti-MLCK antibodies, which preferentially recognize the high molecular-weight EC MLCK isoform. Monitoring of MLCK expression in different cell types with antibodies generated against a unique human EC MLCK N-terminal sequence revealed a high level of expression of the 214-kD enzyme in endothelium, minimal level of expression in smooth muscle, and no expression in skeletal muscle. These data suggest that the novel 214-kD kinase, the only MLCK isoform found in endothelium, may be preferentially expressed in this nonmuscle tissue.

Uteroplacental vascular involvement in recurrent spontaneous abortion

Spontaneous abortion is common in human pregnancy. Recent advances in pregnancy immunology and vascular biology are reviewed with emphasis upon the events associated with recurrent fetal losses. Certain treatment options used to alleviate or prevent some miscarriages are presented and discussed.

Tubular antithrombin at transplantation determines subsequent renal allograft function

BACKGROUND

Antithrombin is found in the microvasculature and tubules of normal and transplanted human kidneys. Although depletion of vascular antithrombin is associated with renal allograft dysfunction, neither the distribution nor clinical significance of tubular antithrombin is known.

METHODS

Changes in tubular antithrombin in biopsy specimens (n=41) obtained from donor kidneys at transplantation were studied immunohistochemically. The relationship between these changes and subsequent graft function was analyzed.

RESULTS

Granular intracellular antithrombin was found only within the proximal tubular epithelium. Allografts with depleted tubular antithrombin at transplantation (n=20) had significantly greater plasma creatinine concentrations at posttransplant days 3 (P < 0.001) and 5 (P < 0.03) than allografts with normal tubular antithrombin (n=21). Indeed, depletion of tubular antithrombin at transplantation correlated with the degree of graft dysfunction at 3 days after transplantation.

CONCLUSIONS

Depleted tubular antithrombin at transplantation is associated with reduced early graft function, and this may identify patients at risk of a complicated follow-up.

Myocardial fibrin deposits in the first month after transplantation predict subsequent coronary artery disease and graft failure in cardiac allograft recipients

PURPOSE

To determine whether fibrin deposition during the first month following cardiac transplantation predicts development of coronary artery disease and graft failure in cardiac allograft recipients.

PATIENTS AND METHODS

We prospectively studied 121 consecutive adult patients who received cardiac transplants between 1988 and 1995. Serial endomyocardial biopsies obtained during the first month posttransplant (2.3 + 0.6 biopsies/patient) were studied immunohistochemically for fibrin deposits. Patients were followed up with annual angiograms (3.2 + 1.7/patient) evaluated with side-by-side comparisons for the presence and progression of coronary artery disease.

RESULTS

All pretransplant biopsies were fibrin-negative; 60 allografts (50%) remained without fibrin, and 61 (50%) contained fibrin during the first posttransplant month. Of allografts with fibrin, 72% developed coronary artery disease, while 27% of allografts without fibrin developed the disease (P <0.001). Coronary artery disease was progressive in 61% of allografts with fibrin, and in 25% of allografts without fibrin (P <0.001). Graft failure was more frequent and time-to-graft-failure occurred earlier in patients whose allografts had fibrin during the first month after transplantation (P <0.001).

CONCLUSIONS

Fibrin in biopsies during the first month after transplantation identifies patients at high risk for developing coronary artery disease or graft failure, thereby allowing the opportunity to initiate preventive procedures.

Endothelial activation and development of coronary artery disease in transplanted human hearts

CONTEXT

The development of coronary artery disease in heart transplants is often associated with graft failure. Early detection of allografts prone to develop this disease is essential to institute new therapeutic approaches that could prolong allograft function.

OBJECTIVE

To determine if early activation of arterial/arteriolar endothelium predicts the development of coronary artery disease, graft failure, or both in transplanted human hearts.

DESIGN

Prospective cohort study.

SETTING

Heart Transplant Center.

PARTICIPANTS

A total of 121 consecutive adult cardiac allograft recipients who received transplants between 1988 and 1995 and were followed up through 1996.

MAIN OUTCOME MEASURES

Development of coronary artery disease and graft failure.

METHODS

Immunocytochemistry was performed on serial endomyocardial biopsy specimens to evaluate endothelial activation markers (intercellular adhesion molecule-1 and histocompatibility antigen HLA-DR) in arteries and arterioles. The presence and progression of coronary artery disease was evaluated by annual coronary angiograms with side-by-side comparisons.

RESULTS

None of the 121 donor hearts showed arterial/arteriolar endothelial activation before transplantation. Arterial/arteriolar endothelial activation was present in 78 and absent in 43 of 121 allografts during the first 3 months after transplantation. The time of appearance and the proportion of biopsy specimens showing endothelial activation during these first 3 months were significantly associated with the risk of developing coronary artery disease, the progression of the disease, and the time required to develop the disease (P<.001). Significantly more patients with arterial/arteriolar endothelial activation died or received a second transplant (P<.001).

CONCLUSIONS

Activation of arterial/arteriolar endothelium in transplanted human hearts predicts development of coronary artery disease and increased risk of graft failure.

Vascular endothelial growth factor expression in transplanted human hearts

Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen thought to play an important role in coronary collateral vessel formation. We used immunocytochemistry to determine VEGF expression in biopsies (n = 283) of transplanted human hearts (n = 109) with and without microvascular fibrin. Measures of vascular fibrin, alpha 2 plasmin-inhibitor (a2Pl), macrophages, neutrophils, and serum cardiac troponin T titers were used to evaluate myocardial damage. Antibody to T lymphocytes was used to evaluate cellular rejection, and HLA-DR, ICAM-1, and PAL-E antibodies were used to assess endothelial cell activation and phenotypic changes in the microcirculation. No VEGF immunoreactivity was detected in control donor hearts without fibrin, but the proportion of biopsies demonstrating VEGF immunoreactivity increased significantly in allografts with increasing fibrin and a2PI reactivity (P = 0.0001). VEGF immunoreactivity was confined to areas of fibrin deposition and was associated with infiltrates of macrophages and neutrophils (P < 0.0001), but not with T cells (P = 0.10). Biopsies with fibrin/VEGF reactivity were associated with increased capillary endothelial cell HLA-DR, ICAM-1, and PAL-E reactivity. In a subset of patients, serum cardiac troponin-T values were greater in patients with VEGF-positive (n = 21) than VEGF-negative (n = 19) biopsies (P = 0.05). Nested RT-PCR demonstrated that biopsies with and without fibrin/VEGF immunoreactivities expressed VEGF121, VEGF165, and VEGF189 variants, with VEGF165 being the dominate variant. These results indicate that endogenous VEGF is expressed locally following vascular thrombosis and myocardial cell damage, and that VEGF expression may be related to endothelial cell activation and phenotypic changes found in the microcirculation of cardiac allografts.

Vascular tissue plasminogen activator and the development of coronary artery disease in heart-transplant recipients

BACKGROUND

An aggressive and potentially fatal form of coronary artery disease may develop after cardiac transplantation. We studied the role of vascular tissue plasminogen activator (t-PA), the primary mediator of fibrinolysis, in the development of this problem.

METHODS

We studied 78 consecutive recipients of cardiac allografts over a five-year period, and we collected follow-up data over a mean (+/- SE) of 32.5 +/- 2.0 months. The patients were studied with ventricular function tests, serial endomyocardial biopsies (16.6 +/- 0.5 per patient), and annual coronary angiography. Measurements of t-PA and its inhibitor were performed immunocytochemically on unfixed cryostat sections of endomyocardial-biopsy specimens with the use of monoclonal antibodies to t-PA and its inhibitor.

RESULTS

In biopsy specimens obtained during the first three months of follow-up, 38 allografts had a normal distribution of t-PA in arteriolar smooth-muscle cells, whereas in 40 allografts there was depletion of t-PA that persisted in subsequent follow-up. Coronary artery disease developed during follow-up in 31 of 40 allografts (78 percent) with depletion of t-PA, but the disease developed in only 9 of the 38 allografts (24 percent) with normal t-PA levels (P < 0.001). Allografts with depletion of t-PA also had the t-PA inhibitor and were at greater risk for earlier and more severe disease than were allografts with normal arteriolar t-PA levels. Twelve patients whose allografts were depleted of t-PA either received a second transplant or died, whereas only one of the patients whose allografts had persistently normal t-PA levels died (P < 0.001).

CONCLUSIONS

These findings reveal an association between the depletion of t-PA from arteriolar smooth-muscle cells and the subsequent development of coronary artery disease and decreased graft survival. Although we cannot be certain about a cause-and-effect relation, our data suggest a possible role for deficient fibrinolysis in the development of coronary artery disease in transplanted human hearts.

Maternal cells in chorionic villi from placentae of normal and abnormal human pregnancies

PROBLEM

We asked if activated macrophages and CD4 positive T lymphocytes in placental chorionic villi with villitis were of maternal or fetal origin.

METHOD

We employed a double antibody immunocytochemical technique on placental sections from three normal and four abnormal pregnancies with small-for-gestational-age infants. All studied placentae were mismatched for the maternal-fetal HLA-DRw 52 antigen. Areas of immunopathology were identified by using a monoclonal antibody to a monomorphic determination on HLA-DR, and the origin of immunological cells in areas of immunopathology was identified by using a monoclonal antibody to a polymorphic determinant on HLA-DRw 52.

RESULTS

We used a double antibody technique that employed monoclonal antibodies to HLA-DR and HLA-DRw 52 antigens and placentae that were mismatched for the maternal-fetal HLA-DRw 52 antigen. We found that the vast majority of immunological cells within villi with inflammation were of maternal origin. Quantitative studies showed that between 75 and 100% of the cells in normal as well as in abnormal pregnancies were of maternal origin, and that abnormal pregnancies had a significantly higher percentage of villi with maternal cellular infiltrates.

CONCLUSION

Our data show unequivocally that cells in areas of placental immunopathology are predominantly of maternal origin, and that abnormal pregnancies are associated with significantly more villi containing immunological cells of maternal origin.

Intercellular adhesion molecule-1 (ICAM-1) and HLA-DR antigens are expressed on endovascular cytotrophoblasts in abnormal pregnancies

PROBLEM

We asked if the lack of normal trophoblastic invasion of spiral arteries in the basal plate of abnormal pregnancies was associated with the expression of HLA-DR antigens and intercellular adhesion molecules (ICAM-1) on endovascular cytotrophoblasts.

METHOD

The basal plates of placentae from 15 normal and 55 abnormal pregnancies, including preeclampsia, small-for-gestational age infants, and mothers with history of secondary recurrent spontaneous abortion, were studied immunocytochemically by using monoclonal antibodies to HLA-DR and ICAM-1. Spiral and uteroplacental arteries were identified by using a triple antibody technique with antibodies to cytokeratin, alpha-smooth muscle actin, and von Willebrand factor to detect cytotrophoblasts, arterial smooth muscle cells, and endothelium, respectively.

RESULTS

Placentae with normal placentation showed the presence of uteroplacental arteries that contained endovascular cytotrophoblasts that were negative for HLA-DR and ICAM-1 antigens. Placentae from abnormal pregnancies showed the presence of spiral arteries without trophoblastic invasion and uteroplacental arteries that were surrounded by numerous macrophages and T lymphocytes. Endovascular cytotrophoblasts in uteroplacental arteries of placentae from abnormal pregnancies reacted with antibodies to HLA-DR and ICAM-1 antigens.

CONCLUSION

Placentae from normal pregnancies show uteroplacental arteries that contain endovascular cytotrophoblasts that do not react with antibodies to ICAM-1 and HLA-DR antigens, and placentae from abnormal pregnancies with uteroplacental arteries that are associated with arteries that do not show physiological changes contain endovascular cytotrophoblasts that react with antibodies to ICAM-1 an HLA-DR antigens. Normal uteroplacental arteries were found to be not surrounded by round cell infiltrates, but uteroplacental arteries associated with arteries that lack physiological changes were surrounded by round cell infiltrates, indicating that round cell infiltrates and endovascular cytotrophoblasts which react with antibodies to ICAM-1 and HLA-DR antigens are associated with abnormal pregnancies. These findings suggest that the cellular infiltrates are associated with endovascular cytotrophoblasts that react with ICAM-1 and HLA-DR antigens.

Natural anticoagulant and fibrinolytic pathways in renal allograft failure

This is an immunocytochemical study of the relationship between depletion of natural anticoagulant and fibrinolytic pathways and allograft survival following renal transplantation. Patients (n = 44) were classified in three groups according to the length of time between transplantation and allograft failure: group 1 (n = 14) failed within a month of transplantation; group 2 (n = 14) failed between one month and one year after transplantation; and group 3 (n = 16) failed after one year of transplantation. Control biopsies were from donor kidneys (n = 16) prior to transplantation. There were no statistically significant differences in recipient age, gender, donor kidney type (living-related versus cadaver), histocompatibility, and plasma cholesterol, triglycerides, or creatinine concentrations between groups. However, group 1 allografts had a greater depletion of the vascular heparan sulfate proteoglycan-antithrombin III natural anticoagulant pathway than allografts in group 2 or 3 (P < or = 0.05), and this depletion was associated with significantly greater fibrin deposition in group 1 than in either group 2 or 3 (P < or = 0.05). All three groups demonstrated severe depletion of tissue plasminogen activator from arteriolar smooth muscle cells and depressed fibrinolysis as evidenced by increased fibrin/plasmin ratios. However, no significant differences were found for either endothelial thrombomodulin or T cell, neutrophil, or macrophage infiltration between the groups. These data indicate that differences in graft outcome may be determined more by compromised vascular function than by the presence of cellular infiltrates.

Antigenic identification of cells in spiral artery trophoblastic invasion: validation of histologic studies by triple-antibody immunocytochemistry

OBJECTIVE

Trophoblastic invasion of spiral arteries in the placental bed is essential for normal human placentation. Because the absence of these physiologic changes is associated with abnormal pregnancies, we developed a simple immunocytochemical approach that allows simultaneous study of three cell types involved in spiral artery changes (i.e., trophoblastic, endothelial, and smooth muscle cells).

STUDY DESIGN

Spiral and uteroplacental arteries in the basal plate of 70 term placentas were studied simultaneously with antibodies to keratin to identify cytotrophoblasts, alpha-smooth muscle actin to identify vascular smooth muscle cells, and von Willebrand factor to identify endothelial cells in 15 normal placentas and 55 placentas from abnormal pregnancies.

RESULTS

Normal term placentas showed keratin-positive, alpha-smooth muscle actin-negative and von Willebrand factor-negative uteroplacental arteries. Most (37/55) placentas from abnormal pregnancies had keratin-negative, alpha-smooth muscle actin and von Willebrand factor-positive spiral arteries. Spiral artery atherosclerosis was keratin negative, alpha-smooth muscle actin positive, and von Willebrand factor positive and was identified in 22 abnormal and 0 normal placentas.

CONCLUSION

Simultaneous identification of three principal cell types involved in human placentation allowed qualitative and quantitative studies of placentas from normal and abnormal pregnancies that validated previous histologic investigations and provided a new approach to detect spiral arterial changes.

Tissue plasminogen activator, plasminogen activator inhibitor-1, and fibrin as indexes of clinical course in cardiac allograft recipients. An immunocytochemical study

BACKGROUND

Tissue-type plasminogen activator (TPA) is the principal activator of plasminogen. Since hemostasis in the microcirculation of allografts is a well-recognized complication of transplantation, we asked (1) whether the distribution and amount of cellular TPA in biopsies of transplanted human hearts are associated with fibrin deposits in and around the microcirculation, (2) whether such changes involve the physiological inhibitors of TPA and plasmin, and (3) whether the presence of these activators and inhibitors of fibrinolysis in tissue is correlated with clinical outcome.

METHODS AND RESULTS

We immunocytochemically quantified the presence of fibrin, plasmin, TPA, and the TPA inhibitor PAI-1 in 938 biopsies from 68 consecutive cardiac allografts over a 54-month period. The localization, distribution, and quantification of TPA in arteriolar smooth muscle cells revealed that 35 of the 68 allografts maintained vascular TPA reactivity consistent with time-zero biopsies of autologous donor hearts: this was designated as the normal TPA group. In contrast, 33 of the 68 allografts significantly lost vascular TPA reactivity compared with time-zero biopsies of autologous donor hearts: this was designated as the depleted TPA group. Analysis of sequential biopsies from both groups during 54 months revealed that the mean cumulative quantitative TPA value for the normal TPA group was 1.0 +/- 0.01, whereas the depleted TPA group value was 1.9 +/- 0.02 (P = .0001), and the mean cumulative quantitative fibrin value for the normal TPA group was 1.0 +/- 0.01, whereas the depleted TPA group value was 1.5 +/- 0.05 (P = .0001). Biopsies of allografts in the depleted TPA group contained endothelial reactivity for TPA-PAI-1 complexes, whereas biopsies from the normal TPA group did not. Plasmin-associated molecules were rarely identified in biopsies of the normal TPA group but were present in the depleted TPA group, and the fibrin-to-plasmin ratio in the normal TPA group always was less than the fibrin-to-plasmin ratio in biopsies from the depleted TPA group. Analysis of demographic and risk factors revealed no significant differences between patients in the normal and depleted TPA groups, but none of the 35 patients in the normal TPA group died or were retransplanted, and 13 of the 33 patients in the depleted TPA group died or required retransplantation (P = .0001).

CONCLUSIONS

Time-zero hearts (n = 68) and 34 of 38 stable allografts contained immunocytochemically detectable TPA only in vascular smooth muscle cells. Twenty-nine of 30 patients with normal TPA in their time-zero biopsies who subsequently developed a poor clinical outcome were found to have depleted TPA in biopsies evaluated during their first postoperative month and remained depleted throughout the study. Of 33 patients with depleted TPA, 39% died or required retransplantation. Depleted arteriolar TPA associated significantly with vascular and interstitial deposits of fibrin, plasmin, and endothelial TPA-PAI-1 complexes. These findings indicate that hemostatic and fibrinolytic pathways are activated in falling allografts, and they reveal evidence of depleted TPA before clinical or histopathological signs of failure. Patients with such allografts were found to be at high risk of death independently of other widely used clinical/laboratory parameters of prediction.

Predominant expression of the beta subunit of prolyl 4-hydroxylase (disulfide isomerase) in human extravillous trophoblasts

Prolyl 4-hydroxylase is a heterodimeric enzyme that is crucial in the biosynthesis of collagen. The beta subunit of this enzyme is a multifunctional protein which is also known as protein-disulfide isomerase. Immunofluorescence and monoclonal antibody (Mab) 5B5 were used to localize the beta subunit in human extraembryonic tissues. The strongest sites of 5B5 reactivity were extravillous cytotrophoblasts in the basal plate, uteroplacental arteries and amniochorion, syncytiotrophoblast displayed variable weaker reactivity. Only a small fraction of placental 5B5 antigen was detected as a component of prolyl-4-hydroxylase by affinity chromatography on immobilized polyproline. The results indicate a difference in the expression of an endoplasmic reticulum marker between villous and extravillous trophoblast. The predominance of 5B5 antigen in extravillous trophoblast could be associated with an increased ability to synthesize collagen or other enzymatic reactions associated with prolyl 4-hydroxylase beta subunit.

Immunoglobulin M antibodies in transplanted human hearts

We have studied 56 human hearts before and after transplantation for the presence of immunoglobulin M. None of the 56 time-zero biopsy specimens studied contained immunocytochemically detectable immunoglobulin M, but they all had immunoglobulin M deposits on vascular endothelial cells after transplantation. The vascular location of immunoglobulin M was confirmed in double-antibody experiments with antibodies to von Willebrand factor and immunoglobulin M. None of the immunoglobulin M antibody reactivity was shown to colocalize with complement. Biopsy specimens from 29 of the 56 patients contained abundant deposits of immunoglobulin M. These patients were clinically stable, and only one of them has died. Biopsy specimens from 27 of the 56 patients had scant deposits of immunoglobulin M. These patients were clinically unstable; eight of them have died, and one has undergone retransplantation. In addition, biopsy specimens from stable allografts contained fewer fibrin deposits than biopsy specimens from unstable grafts, suggesting a protective role for non-complement fixing immunoglobulin M. The observation that immunoglobulin deposits were found soon after transplantation prompts us to consider them to be natural antibodies. Efforts to identify the antigen for immunoglobulin M natural antibodies in heart transplant recipients are currently under study.

Tissue plasminogen activator in human cardiac allografts

The activation of hemostasis and fibrinolysis frequently is observed in allografted organs. Plasminogen is activated by urokinase and tissue plasminogen activator (tPA). We have studied human hearts before and after transplantation to determine if fibrin deposition within the microcirculation is associated with a depletion of myocardial tPA, and if such depletion of tPA is associated with decreased fibrinolysis. We found that tPA in pretransplanted hearts and in biopsies from hearts of most patients with a stable clinical course is confined to arterial and arteriolar smooth muscle cells. The depletion of smooth muscle cell reactivity was associated with microvascular fibrin deposition in unstable allografts, and the appearance of endothelial cell tPA reactivity heralded a bad prognosis. Successful medical management was signaled by a loss of endothelial tPA reactivity and a return of tPA reactivity in arterial and arteriolar smooth muscle cells. These findings indicate a central role for tPA in maintaining the integrity of the microcirculation in transplanted human hearts.

Vascular lesions in biopsy specimens devoid of cellular infiltrates: qualitative and quantitative immunocytochemical studies of human cardiac allografts

Biopsy specimens from 80 cardiac allografts were studied immunocytochemically with nine antibodies selected to identify cellular, immunologic, and vascular aspects of rejection. Results from these experiments were converted to a numeric base and used to calculate rejection indexes for each of these aspects of rejection. Pretransplantation biopsy specimens of donor hearts were studied to determine normal values, and clinical, catheterization, and conventional biopsy findings were used to classify patients as stable or unstable. The standard deviation of cellular and immunologic reaction indexes were overlapping for stable and unstable patients, but the vascular indexes for these patient groups were significantly different, suggesting that vascular damage defines clinical instability in cardiac allograft recipients. To study the vascular index in the absence of cellular infiltrates, biopsy specimens from 80 allografted hearts were selected to represent 40 patients with cellular infiltrates and 40 patients devoid of infiltrates. The results of this analysis revealed no difference in the vascular index between hearts that contained or did not contain infiltrates; the spectrum of vascular damage between the groups ranged from trivial to severe, suggesting that vascular damage was not dependent on cellular infiltrates. Concluding that these were independent events was not possible, however, because none of the hearts continuously were devoid of cellular infiltrates. Two groups of patients with significantly different vascular indexes then were studied for a systemic manifestation of coagulation by measurement of their thrombin times. The group with low vascular index was found to have significantly prolonged thrombin times compared to the group with high vascular index, and a trend to less prolongation of thrombin times was observed in another group with high cellular index. The relation of these results with cardiac allograft vasculopathy is not established, but the results suggest hitherto unexplored roles for quantitative expressions of hemostasis, fibrinolysis, and anticoagulation in the pathophysiology of vascular disease in allografts.

Modulation of vascular antithrombin III in human cardiac allografts

The natural anticoagulant pathway involving heparan sulfate proteoglycan and antithrombin III (ATIII) was studied in serial biopsies from 90 cardiac allograft recipients. The ATIII component of this pathway was identified immunocytochemically on venous endothelium and arterial smooth muscle cells and intima of normal donor hearts and stable allografts. Unstable grafts lacked vascular ATIII and contained fibrin deposits. Neither stable nor unstable grafts had ATIII-reactive capillary endothelium. Grafts with absent vascular ATIII could (1) result in death, (2) revert to an arterial/venous ATIII distribution or (3) develop ATIII-reactive capillary endothelium. The development of ATIII-reactive capillaries was associated with a survival advantage, and such reactivity seemed to be promoted by heparin.

Laboratory-clinical correlates of time-associated lesions in the vascular immunopathology of human cardiac allografts

Ninety cardiac allograft recipients were studied for clinical and functional parameters during a 40-month period. Baseline histologic and immunocytochemical data were obtained from donors' hearts before transplantation, and serial endomyocardial biopsy specimens were studied histologically for cellular infiltrates and immunocytochemically for complement and immunoglobulin deposits and for components of the hemostatic, fibrinolytic, and natural anticoagulant pathways. Results were grouped according to the time from transplantation: the first 3 months, 4 to 21 months, and 22 to 40 months. Each group was evaluated for most frequently obtained immunocytochemical findings and results relevant to clinical-laboratory cooperation in patient management. During the first 3 months, findings of biopsy specimens from allografts that subsequently were going to be problem cases revealed depleted tissue plasminogen activator in arteriolar smooth muscle cells, and recipient IgM that was deposited on donor endothelium of stable grafts was diminished or absent in unstable allografts. In addition, vascular deposits of activated complement components were identified in 50 of 70 allografts. From 4 through 21 months after transplantation, vascular deposits of complement rarely were identified (even in patients who previously had positive biopsy specimens), and the principal vascular lesion was fibrin deposits with impaired anticoagulant pathways and inadequate fibrinolysis, usually without associated cellular infiltrates. From 22 through 40 months after transplantation, the principal vascular lesion was graft-induced atherosclerosis. These immunocytochemically defined qualitative and quantitative changes in unstable or failing allografts form a time-related spectrum of lesions that encompasses the emerging diagnostic entity of vascular rejection.

Immunological studies of lactoferrin in human placentae

Lactoferrin (LF) and transferrin (Trf) are glycoproteins with strong affinities for ferric ions. Human syncytiotrophoblastic membranes analyzed by enzyme linked immunosorbent assay (ELISA) and immunoblotting were negative with monoclonal and polyclonal antibodies to LF. Immunohistological studies of 35 normal placentae showed that LF was absent from the trophoblast basement membranes, stroma and fetal stem vessel endothelium, but positive cells were occasionally noted in intervillous spaces and fetal stem vessels. In contrast, many LF-positive cells were identified within areas of immunopathology identified by the presence of T cells, HLA-DR-positive macrophages and platelets. Double-antibody experiments showed that the LF-positive cells in these areas reacted with CD15 and CD16 monoclonal antibodies (mAbs), indicating that the cells were polymorphonuclear neutrophils (PMN). PMN from peripheral blood analyzed by flow cytometry and immunocytology also showed reactivities with anti-LF, CD15 and CD16 and we consistently found that circulating PMN reacted better than placental PMN with antibodies to MHC class I antigens and gp 100, (CD67), which is a neutrophil activation marker. PMN adherent within placentae had no detectable MHC class I or CD67 antigens. These findings suggest PMN adherent to placental tissues down-regulate or alter plasma membrane markers. LF appears to play a role in placental inflammation, for LF-positive cells were significantly enriched in areas of immunopathology.

Expression of CD59, a human complement system regulatory protein, in extraembryonic membranes

CD59 (leukocyte cluster of differentiation antigen 59), is a phosphatidylinositol glycan-anchored membrane protein that inhibits lysis of cells by terminal complement system components. To further define complement regulatory proteins relevant to pregnancy, this study characterized the expression of CD59 in human extraembryonic membranes. Immunohistology with CD59 monoclonal antibody MEM-43 showed that this molecule was normally present on the apical surface of the syncytiotrophoblast, on extravillous cytotrophoblast, and amniotic epithelium. Immunoblotting confirmed that first and second trimester syncytiotrophoblast microvilli (STM) contained a glycoprotein similar in mass and glycosylation to CD59 from adult cells and tissues. Reactivities of STM with MEM-43 in ELISA were 2- to 6-fold higher than those of kidney, erythrocyte and platelet membranes. Term placental STM from recurrent spontaneous aborting patients after immunotherapy, reacted with MEM-43 in ELISA similarly to STM from normal individuals. Plasmas from pregnant women and umbilical cords had 50% or greater reactivity with MEM-43 than did normal plasmas. CD59 could help protect extraembryonic epithelia from damage by complement in maternal blood and amniotic fluid. The apical location of CD59 reflects the immunological roles and functional polarization of plasma membranes in the syncytiotrophoblast.

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.

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.

Vascular events in placentae and organ allografts

This investigation explores the transplantation analogy of placentae with allografted human organs. Biopsies of cardiac and renal allografts and placentae were studied immunocytochemically with antibodies to components of the immunological, coagulational, anticoagulational, and fibrinolytic systems. Cellular rejection of cardiac and renal allografts was identified by infiltrating lymphocytes and macrophages. This was accompanied by vascular damage characterized by loss of endothelial anticoagulant pathways, vascular deposits of fibrin, and depletion of arterial tissue plasminogen activator (tPA). Failing allografts, including placentae from abnormal pregnancies, demonstrated coagulation/fibrinolytic changes consistent with vascular rejection, regardless of the presence of cellular infiltrates. An IgM autoantibody to allogeneic endothelium was associated with vascular protection. Its presence in cardiac and renal transplant biopsies was associated with an absence of fibrin deposits, and its absence was associated with vascular damage. Atherosclerosis commonly was identified in allograft biopsies (including placentae from abnormal pregnancies). These changes were shown in serial biopsies of transplanted hearts to be preceded by or associated with diminished IgM autoantibody, impaired endothelial anticoagulant pathways, vascular fibrin deposits, and depleted arterial reactivity for tPA. These results indicate the transplantation analogy of pregnancy should be viewed more specifically as vascular smooth muscle cell and endothelial responses to as yet unidentified microenvironmental stimuli.

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.

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.

Microvascular perturbations in human allografts: analogies in preeclamptic placentae

The thromboresistance of endothelium is maintained as long as natural anticoagulant pathways are functionally present on endothelial plasma membranes. The principal anticoagulant pathways in human hearts and kidneys are thrombomodulin (TM) and heparan sulfate proteoglycan-antithrombin III (HSPG-ATIII). The downregulation of TM or the loss of ATIII is associated with fibrin deposition. This sequence of events occurs when stable allografts of hearts or kidneys become unstable or rejected. Human placentae do not contain the HSPG-ATIII natural anticoagulant pathway, but the TM system is uniformly represented on endothelium of normal chorionic villi. However, many villi in placentae from preeclamptic pregnancies contain thrombomodulin-negative endothelium, and these vessels contain fibrin thrombi. These thrombi compromise blood flow through the placental microcirculation and are associated with ischemic changes either with or without the presence of cellular infiltrates.

The complement system in human reproduction

Regulation of the complement system in reproduction is unique inasmuch as reproductive tissues represent the only condition where allogeneic interactions occur naturally. Both allogeneic extraembryonic membranes and semen that contact and interact with maternal cells and tissues must avert complement-mediated damage to ensure reproductive success. Several regulators of complement activation exist. Membrane cofactor protein (MCP) and decay accelerating factor (DAF) inactivate C3 and C5 convertases on cell surfaces. In addition, CD59 inhibits the membrane attack complex (MAC) of the complement cascade. Strong expression of these membrane glycoproteins by trophoblast and amniotic epithelium has been observed. MCP, DAF, and CD59 likely safeguard extraembryonic tissues from complement damage originating from maternal and fetal blood or amniotic fluid. Different reproductive tract fluids vary in complement levels. With the exception of ovarian follicular fluid, these levels are generally much less than those in blood. Endometrial and cervical content of C3 appear to be regulated by hormones. These observations suggest that the effects of complement activation may vary in reproductive tissues. MCP is absent from the surfaces of oocytes. Sperm express MCP and DAF in discrete areas that would not be associated with the known complement-regulatory functions of these proteins. Seminal plasma contains MCP and the MAC inhibitor SP-40,40 but not DAF.SP-40,40 may exemplify how complement-regulatory proteins perform alternative functions as it interacts with molecules other than complement components. We have reviewed aspects of the complement system that relate to allogeneic interactions in reproduction and that suggest fruitful areas for further research.

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.