Venous thromboembolism in the antiphospholipid syndrome: management guidelines for secondary prophylaxis

Venous thromboembolism (VTE) in patients suffering from the antiphospholipid syndrome (APS) has been reported in almost any location of the vessel tree and the risk of recurrences has been found in several studies to be more closely associated with the presence of lupus anticoagulant than with the positivity for anti-cardiolipin antibodies. The thrombophilic state of APS raises the problem of the secondary prophylaxis to avoid VTE recurrences. For APS patients with VTE, published data appear to support a longer warfarin treatment if compared with the standard management of antiphospholipid (aPL)-negative patients with VTE. The question of how long oral anticoagulant treatment should be continued for APS patients, however, remains unanswered. Concerning the intensity of anticoagulation, several authors recommend a target international normalized ratio (INR) between 3.0 and 4.0 to efficiently protect from VTE recurrences. A recent decision analysis study does support such a suggestion. On the contrary, in a few prospective studies regimens with lower target INRs appear to be effective, and some authors therefore recommend a target INR of between 2.0 and 3.0. Specific large and prospective trials are needed to address this question. Until such information becomes available, individualized treatment according to the patient's individual risk factors for both bleeding and thrombosis is the general practice.

Antiphospholipid antibodies and renal transplantation: a risk assessment

Data from 110 transplanted patients show that the presence of antiphospholipid antibodies (aPL) at the time of transplantation is an important risk factor for early renal allograft failure. Sera were tested for IgG, IgM and IgA to CL, PS, PE and PC. Haemodialysis patients had a significantly higher incidence of aPL compared to patients who did not receive haemodialysis (P = 0.0171). aPL-positive ESRD patients on peritoneal dialysis (CAPD) or who had never received haemodialysis were at maximal risk; 100% failure (P = 0.0022). aPL-positive patients receiving haemodialysis were not at such risk. Biopsy findings from the failed kidneys show abundant fibrin deposition in the microvasculature. Serial blood samples from transplanted patients showed aPL titres to decrease immediately after transplant and increase after removal of the failed graft, indicating that aPL specifically target the allografts. To confirm this, we were able to isolate aPL from a failed graft after transplant nephrectomy. Ninety-seven per cent of the aPL-positive patients' historic pre-transplant serum samples demonstrated the presence of the same aPL specificity detected in the final crossmatch sera. The exposure to heparin during haemodialysis suggested to us that heparin reduces the risk of clotting in aPL positive transplant candidates. To lessen the risk of graft loss in aPL positive kidney transplant patients (including CAPD), subcutaneous heparin was administered peri- and post-operatively. To date, none of the heparin-treated aPL-positive transplanted patients suffered an early graft loss. Further, they experienced fewer rejection episodes requiring biopsy and thus are prescribed less steroid therapy than patients not treated with heparin.

Anti-annexin A5 Antibodies in Reproductive Failures in Relation to Antiphospholipid Antibodies and Phosphatidylserine

PROBLEM

The presence of IgG anti-annexin A5 (IgGalphaA5) and/or antiphospholipid antibodies (aPL) are risk factors associated with recurrent spontaneous abortion. Problems are whether IgA antiannexin A5 (IgAalphaA5) is pathogenic, and how IgGalphaA5 works.

METHOD OF STUDY

Blood samples from 238 patients with early recurrent spontaneous abortion, 48 patients with recurrent in vitro fertilization-embryo transfer failure, 179 non-pregnant women and 120 pregnant controls were tested for IgAalphaA5 by enzyme-linked immunosorbent assay. We also determined if IgGalphaA5 appeared coincident with aPL. The antigenic epitope(s) recognized by IgGalphaA5 was investigated.

RESULTS

We observed no difference between patients and controls for IgAalphaA5. The prevalence of IgGalphaA5 was not different statistically between patient samples with or without aPL. Patient IgGalphaA5 bound annexin A5 when the latter was free/unbound but not when annexin A5 was associated with phospholipid.

CONCLUSIONS

The IgAalphaA5 does not appear to be pathogenic. IgGalphaA5 works to make a complex with annexin A5 without relation to aPLs, which may reduce annexin A5 available for binding to trophoblast.

Antiphospholipid antibodies in implantation failures

PROBLEM

The amino phospholipids (PL), phosphatidylserine (PS) and phosphatidylethanolamine (PE) are distributed asymmetrically in the plasma membranes of eucaryotic cells. This arrangement involves active transport of PS and PE from the outer to inner membrane leaflet by an aminophospholipid translocase (flipase). Cell activation, injury and programmed cell death (apoptosis) cause collapse of the PS/PE asymmetry by activation of another enzyme system, scramblase. Unlike other cells, the developing trophoblast exteriorizes PS during its differentiation.

METHODS OF STUDY

An analysis of published and unpublished data.

RESULTS

The trophoblast is targeted by antiphospholipid antibodies (aPL), especially to PS (aPS). Cardiolipin is not present in the trophoblast plasma membrane, nonetheless, anticardiolipin (aCL) has been implicated in trophoblast pathology. The aPS and aCL are often crossreactive. Both animal and in vitro experimental models have shown monoclonal and polyclonal aPS and aCL to specifically destroy trophoblast, inhibit syncytium formation, halt human chorionic gonadatropin (hCG) production, and limit trophoblast invasion. Antibodies to PE (aPE) have not been well characterized, however, recent reports from several independent laboratories document that aPE are associated significantly with very early (embryonic) recurrent pregnancy loss (RPL). Umeda and coworkers have shown that during cytokinesis (late telophase) of Chinese hamster ovary (CHO) cells, formation of PE rafts in cleavage furrows is required for completion of cell division and formation of daughter cells. This raises the question whether aPE might interfere with implantation and cell division during embryogenesis.

CONCLUSIONS

A role for aPL in implantation failure and occult pregnancy loss constitutes the basis of this overview.

Certain autoantibodies to phosphatidylethanolamine (aPE) recognize factor XI and prekallikrein independently or in addition to the kininogens

Recent evidence shows that many antiphospholipid antibodies (aPL) to negatively-charged phospholipid (PL) do not target anionic PL per se, but are specific for anionic PL-binding plasma proteins, for example, beta(2)-glycoprotein I (beta(2)-GPI) and prothrombin. We also reported that certain antiphosphatidylethanolamine antibodies (aPE) are not specific for phosphatidylethanolamine (PE) per se, but are directed to PE-binding plasma proteins, high molecular weight kininogen (HK), and low molecular weight kininogen (LK). Additional studies have shown that certain aPE failed to recognize purified kininogens but continued to produce aPE ELISA reactivity in the presence of semipurified HK preparations containing the HK binding proteins, factor XI (FXI) and prekallikrein (PK). We therefore investigated if certain of these aPE recognized FXI and/or PK. In this study we observed that aPE can recognize contact proteins FXI and PK independently or in combination with HK. Since contact proteins such as HK, PK and factor XII (FXII) have anti-coagulant and profibrinolytic functions, the pathophysiological role of aPE has yet to be elucidated. We propose that aPE of different specificities may initiate or promote characteristics pathological conditions in patients with thrombosis or recurrent pregnancy losses.

Different antiphospholipid antibody specificities are found in association with early repeated pregnancy loss versus recurrent IVF-failure patients

PROBLEM

Patients having in vitro fertilization and embryo transfer (IVF-ET) failures show an increased incidence of antiphospholipid (aPL) antibodies; but controversy exists whether aPL can induce IVF-failure. This study was designed to compare aPL specificities between recurrent IVF-failure patients versus repeated early pregnancy loss (RPL) patients.

METHOD OF STUDY

Anticardiolipin (aCL), lupus anticoagulant (LA), antiphosphatidylserine (aPS), antiphosphatidylethanolamine (aPE), and antinuclear antibodies (ANA) were measured in 74 recurrent IVF-ET failure patients and compared with 273 early RPL patients ( < 10 weeks).

RESULTS

An increased incidence of IgG-aPE and ANA was observed for both groups in comparison with controls. Patients with recurrent IVF-ET failure showed a significantly higher prevalence of IgG-aPS (P = 0.02) and IgG-aCL (P = 0.02) when compared with early RPL patients or controls.

CONCLUSIONS

IgG-aPS and IgG-aCL may be responsible for some IVF-failures. Additional studies are needed to clarify the pathogenic role of IgG-aPS and IgG-aCL on IVF-ET failure.

Anti-annexin V antibodies in patients with early pregnancy loss or implantation failures

OBJECTIVE

To describe the prevalence of annexin V antibodies (aANX) in women with early recurrent pregnancy losses (RPLs) or recurrent IVF-ET failure.

DESIGN

Retrospective data analysis.

SETTING

Tokai University Hospital, Kanagawa, Japan.

PATIENT(S)

Two hundred thirty-eight patients with RPLs, 48 patients with recurrent IVF-ET failure and 179 nonpregnant and 120 pregnant control group women.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

ELISA was used to measure autoantibodies to annexin V.

RESULT(S)

An ELISA system developed for aANX revealed a dose-dependent relationship between annexin V and aANX. The positive/negative cutoff was set at 7 multiples of the median based on the 99th percentile of normal nonpregnant control group patients. Patients with RPLs (5.5%) or recurrent IVF-ET failure (8.3%) had a significantly increased incidence of aANX (IgG) compared with normal nonpregnant (1.1%) or pregnant control group women (0), whereas the prevalence of aANX between both patient groups or between both control groups was not statistically different. Specificity was confirmed by absorption studies using annexin V and by immunoblots.

CONCLUSION(S)

Our data show that aANX are associated with both RPLs and IVF-ET failure. We propose that anti-annexin V antibodies should be considered a risk factor for these reproductive failures.

Left ventricular assist system recipients exposed to bovine thrombin preparations have a higher frequency of antiphospholipid antibodies than nonexposed recipients

After left ventricular assist system (LVAS) placement, recipients often develop antiphospholipid antibodies (aPL) that are associated with thrombosis. Fibrin glue containing a bovine thrombin preparation is used routinely in LVAS placement surgery. We investigated whether exposure to the thrombin preparation is responsible for stimulating aPL development in LVAS recipients. Pre-LVAS and weekly post-LVAS sera from six fibrin glue-exposed LVAS recipients and five nonexposed recipients were tested by enzyme-linked immunosorbent assay for IgG, IgA, and IgM anti-phosphatidylserine (aPS), anticardiolipin (aCL), anti-phosphatidylethanolamine (aPE), and anti-phosphatidylcholine (aPC). Fibrin glue exposed recipients developed a significantly greater number of aPL than the nonexposed recipients (24 vs. 8; p = 0.0069). In particular, a higher frequency of IgG aCL (6/6 vs. 1/5; p = 0.015) and IgG aPE (4/6 vs. 0/5; p = 0.045) were noted. Exposure to the bovine thrombin component of fibrin glue seems to stimulate aPL development in LVAS recipients.

Spectrum of antiphospholipid antibodies (aPL) in patients with cerebrovascular disease

BACKGROUND

The association of stroke and antiphospholipid antibodies (aPL) other than anticardiolipin antibodies (aCL) is not well documented.

OBJECTIVE

To report the distribution of aCL, antiphosphatidylethanolamine (aPE), and antiphosphatidylserine (aPS) aPL among patients with symptomatic cerebrovascular disease evaluated by our Stroke Service at Indiana University Hospital from January 1997 to November 1999.

METHODS

We retrospectively reviewed medical records from 1997 to 1999 at Indiana University Hospital for all patients with symptomatic cerebrovascular disease using the International Statistical Classification of Diseases, 9th Revision, (ICD-9) codes. We identified patients with elevated titers of aPL. Sera from these patients were obtained within the first 30 days of the index event. We included only those patients for whom the serum samples were tested in a single laboratory by an in-house enzyme-linked immunosorbent assay (ELISA) for immunoglobulin G (IgG) immunoglobulin A (IgA) and immunoglobulin M (IgM) aCL, aPE, and aPS. We examined the clinical presentation, stroke risk factors, associated rheumatologic disorders, and distribution of aPL specificity and isotype.

RESULTS

Thirty-four of 185 patients, 26 women (76%), with a mean age of 46 years, and 8 men (24%) with a mean age of 46 years, had aPL. Nine patients had transient ischemic attacks (TIA), 25 suffered strokes, 23 had ischemic infarcts, and 2 had hemorrhagic infarcts (1 had a superior sagittal sinus thrombosis with bilateral hemispheric hemorrhagic infarcts, and one had bilateral hemorrhagic infarcts associated with systemic lupus erythematosus [SLE]). Six patients had SLE. The most common stroke risk factors were cigarette smoking (38%) and arterial hypertension (26%). Approximately two thirds (60%) of patients had a single positive aPL finding: aPE in 35%, aCL in 18%, and aPS in 6%. Multiple specificities were seen in 40%. IgA was the only aPL antibody isotype detected in 26% of the patients, IgG was the lone isotype in 24%, and IgM alone in 12%. Multiple aPL isotypes were detected in 38% of patients. Five patients (15%) presented with aPE IgA as the exclusive aPL.

CONCLUSION

In our series, aPE was the most frequent finding in stroke patients who were suspected to have an associated aPL syndrome. These specific types of aPL may be present relatively often in stroke patients and are often not assessed. Further studies are needed to determine how specific these aPL are in stroke versus other acute illnesses and versus healthy controls, and how these aPL are associated with stroke risk.

Antiphospholipid antibodies. Risk assessments for solid organ, bone marrow, and tissue transplantation

The literature pertaining to transplantation of solid organs, bone marrow, and other tissues in aPL-positive patients has been reviewed. The effects that aPL have relative to BMT are altogether different than those ascribed to solid organs and tissues. By definition, the transplantation of allogeneic bone marrow serves to reconstitute the recipient with a completely new and genetically different repertoire of antibody-producing cells. Previously aPL-positive bone marrow recipients become aPL-negative subsequent to transplantation assuming that the marrow donor is aPL-negative. These observations are the basis for contemporary experimental approaches to curing certain autoimmune diseases with BMT. Similarly, it would follow that an aPL-negative patient provided cells from an aPL-positive donor could become aPL-positive and suffer increased risk for thrombosis. From the data provided in most of the non-bone marrow publications, the presence of aPL should be considered a grave risk factor for any potential solid organ or tissue transplant candidate. Peritoneal dialysis patients seem to be at maximal risk. Given the serious emotional and economic impact of irreversible thrombotic loss suffered by organ transplant recipients, these factors alone should justify the modest expense of pretransplant aPL screening. In the United States, the average cost of losing a kidney transplant to aPL-associated thrombosis was estimated from 1996 data to be $82,000. The cost of losing a heart or liver is measured not only in dollars but often in the patient's life. The encouraging news, however, is that once aPL are identified before transplantation, prophylactic anticoagulation seems to be capable of forestalling untoward aPL-associated allograft events. Clearly, much remains to be discovered in exploring the pathobiologic characteristics of aPL in the laboratory as well as in neutralizing their procoagulant effects at the bedside.

Acceptability of the female condom in different groups of women in South Africa--a multicentred study to inform the national female condom introductory strategy

OBJECTIVES

To assess the acceptability of the female condom to different groups of women and their partners in South Africa.

DESIGN

Descriptive, cross-sectional study.

SETTING

Multicentre study conducted in five sites.

SUBJECTS

The study recruited 678 women from five centres to an acceptability trial of the female condom. Acceptability and successful use varied between the centres.

OUTCOME MEASURES

Factors affecting successful use and willingness and intention to use the method again.

RESULTS

In total, 209 women used the condom at least once. Discontinuation rates were high, with partner reluctance to try the method as the main reason given for discontinuation at all sites. Women who had previous experience with the male condom or who received a more intensive training session generally found the device easier to use. The main issues concerning women were over-lubrication (27%) and concern that the device was too large (28%). The majority of women said that they would be interested in using the method again (86%) and would recommend it to friends (95%).

CONCLUSIONS

Overcoming partner opposition is an important issue to address when introducing the method. The study was used to address the national introductory strategy of the female condom, which began in 1998.

Risk of early renal allograft failure is increased for patients with antiphospholipid antibodies

Renal allograft thrombosis can cause transplant failure. Because antiphospholipid antibodies (aPA) are associated with thrombosis, we investigated pretransplant sera from patients with early renal allograft failure to determine if aPA were present. Fifty-six final cross-match (FxM) sera from patients whose transplant failed within 16 days were compared to FxM sera from the next sequential transplant patients. The sera were tested for IgG, IgM, and IgA antibodies to cardiolipin, phosphatidylserine, and phosphatidylethanolamine. aPA were identified in 57% of FxM sera from patients with early non-function versus 35% of FxM sera from patients with functioning grafts (P = 0.02). Historical sera from 11 aPA-positive patients contained aPA up to 18 months prior to transplantation. Since aPA were present in historical sera, testing for aPA can identify certain patients at risk for early allograft failure. The involvement of aPA in early allograft loss is supported by studies demonstrating aPA recovery from an explanted failed transplant.

Report of a new DRB1*13 allele: DRB1*1336

This brief communication describes the characterization of a new allele, DRB1*1336.

Decreased suppression of antibody-dependent cellular cytotoxicity by seminal plasma in unexplained infertility

OBJECTIVE

To determine whether seminal plasma (SP) from unexplained infertile males has different suppressive activity on antibody-dependent cellular cytotoxicity (ADCC) than SP from fertile males or SP from males of couples with known infertility factor.

DESIGN

Comparative clinical/experimental study.

SETTING

In vitro fertilization program in a university hospital and a hospital research laboratory.

PATIENT(S)

A total of 245 SP samples from 174 infertile and 16 fertile couples were compared.

INTERVENTION(S)

SP suppression of ADCC was measured by using human 51chromium-labeled red blood cells (RBC), sensitized with IgG-rabbit-anti-human-RBC as targets and peripheral blood lymphocytes as effector cells.

MAIN OUTCOME MEASURE(S)

Suppressive activity of each sample was determined by calculating 51Cr-release in the presence and absence of SP.

RESULT(S)

When analyzed with respect to sperm number, motility, and morphology, suppressive activities of samples with normal semen analyses (n = 142) were significantly higher (x = 37% +/- 14%) than suppressive activities of abnormal samples (n = 103; x = 32% +/- 13%). There was no strong correlation of suppressive activity to other semen parameters. Within the andrologically normal males, SP from the unexplained infertile couples (n = 15) showed significantly lower suppressive activity (x = 24% +/- 11%) compared with the SP from fertile males (n = 16; x = 35% +/- 13%) and from couples with female infertility factor (n = 65; x = 39% +/- 14%).

CONCLUSION(S)

Loss of suppressive activity is associated with unexplained infertility, even in male patients who previously were considered normal by traditional methods of semen analysis.

Structural integrity of the female condom after multiple uses, washing, drying, and re-lubrication

Establishing the safety of re-using the female condom could significantly increase women's access to barrier methods especially in poorer countries. In this study, the structural integrity of female condoms was tested (n = 295) after multiple acts of vaginal intercourse. Fifty women were recruited to the study. Each woman re-used one condom up to eight times and washed, dried, and re-lubricated between each use. Structural integrity was measured using standard quality control testing; water-leakage, air-burst, and seam tensile strength. All results were compared to the United States Food and Drug Administration (US FDA) standards for an unused female condom. The results of the structural integrity tests for all cycles were above the FDA minimum standards for seam strength and burst tests. There was no deterioration detected in condoms used 8 times when compared to new female condoms in these tests. Five holes were detected by the water leakage test across all cycles, of which three were detected by the subjects themselves and reported to the investigators, therefore, giving a breakage rate of 1.7%. The holes were not associated with increased number of uses. This study provides further evidence that suggests the structural integrity of the female condom after multiple use is still within FDA minimum standards, although random holes resulting from handling occur infrequently with the re-use procedure.

Henoch-Schönlein purpura and stroke: antiphosphatidylethanolamine antibody in CSF and serum

A 15-year-old girl with features of Henoch-Schönlein purpura and brain infarct had a transient IgA antiphosphatidylethanolamine antibody (aPE) in her serum and CSF that disappeared 5 months after presentation. Serum aPE is known to be associated with thrombotic events. The authors found no aPE in the CSF of two control individuals or in the serum of two patients with active Henoch-Schönlein purpura without neurologic involvement. The patient may represent a variant of antiphospholipid antibody syndrome.

Advances and research directions in the prevention of mother-to-child HIV-1 transmission

Although substantial progress has been made in preventing mother-to-child HIV-1 transmission in the past decade, critical research questions remain. Two perinatal epidemics now exist. In more-developed countries, integration of prenatal HIV-1 counselling and testing programmes into an existing antenatal infrastructure, availability of effective antiretroviral prophylaxis, and access to infant formula have resulted in new perinatal infections becoming rare. However, identification of missed prevention opportunities, the causes of prophylaxis failure, and the potential effects of in-utero antiretroviral exposure have become a priority. In less-developed countries, antenatal care is limited, testing programmes are almost non-existent, effective interventions remain unimplemented, and prevention of postnatal transmission through breastmilk while maintaining adequate infant nutrition is a major dilemma. The challenge for the next decade is to simultaneously address questions relevant to both epidemics while bridging the gap in prevention of perinatal transmission between more-developed and less-developed countries.

Immunochemical analysis of polyspecific antibodies in patients exposed to bovine fibrin sealant

BACKGROUND

Patients exposed to bovine thrombin preparations in fibrin sealant often develop antibodies to bovine coagulation proteins, which cause significant bleeding by cross-reacting with human homologues. Recipients of our left ventricular assist system (LVAS) routinely are exposed to fibrin sealant; therefore, we determined whether they developed antibodies.

METHODS

We compared sera from 6 LVAS recipients exposed to fibrin sealant (THROMBOGEN, Johnson & Johnson, Arlington, TX ) during LVAS placement to that of 5 nonexposed LVAS recipients. Pre-LVAS and weekly post-LVAS sera were tested for immunoglobulin (Ig)G, IgA, and IgM reactivity to THROMBOGEN by enzyme-linked immunosorbent assay. Peak IgG and IgA reactive sera were characterized by immunoblotting.

RESULTS

All patients exposed to THROMBOGEN developed antibodies: 5 developed IgG, 4 IgA, and 3 IgM. In contrast, nonexposed patients did not develop antibodies. Only some antibody reactivity was contributed by antithrombin or antifactor V antibodies. Silver stain sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses of THROMBOGEN showed more than 18 bands, many of which were recognized in Western blot by positive patient sera.

CONCLUSIONS

We found both IgG and IgA polyspecific antibody responses in patients exposed to bovine thrombin preparations.

Changes in platelet activation associated with left ventricular assist system placement

BACKGROUND

Thromboembolic and hemorrhagic complications are common in patients after left ventricular assist system (LVAS) placement. Platelet physiology may be involved in these complications.

METHODS

Using flow cytometry, expression of CD62P and CD63 were analyzed as markers of platelet activation. Binding of annexin V was analyzed to determine platelet membrane asymmetry. Results from two patients who received a Novacor LVAS as a bridge to transplantation are reported.

RESULTS

Patients' platelets showed increased CD62P and CD63 expression, yet annexin V binding was not increased. They also revealed suppression of thrombin activation following LVAS placement, which approached normal after transplantation. Heparin suppressed thrombin activation, whereas aspirin or dipyridamole did not. Suppression was attenuated by protamine sulfate and heparinase.

CONCLUSIONS

Following LVAS placement, resting platelets demonstrate increased expression of activation markers.

Qualitative and quantitative studies of autoantibodies to phospholipids in diabetes mellitus

Diabetes mellitus is associated with vascular and neurological complications. We have investigated the presence of antibodies to phospholipids and to phospholipid binding plasma proteins in blood samples collected from 68 clinically and biochemically characterized type I and type II diabetic patients and from 252 healthy blood donor controls. Each sample was analysed for antibodies to three phospholipids (cardiolipin, phosphatidylserine and phosphatidylethanolamine), the antibody isotypes (IgA, IgG and IgM), and whether antibody activity was plasma protein-dependent. Patients were considered to have anti-phospholipid antibodies when one or more of these 18 tests was found above predetermined control values. The results of these experiments revealed an increased incidence of anti-phospholipid antibodies in diabetic patients compared with control subjects. The incidence of IgA isotype to phosphatidylethanolamine was higher than the incidence of other isotypes to other phospholipids, and their reactivities were independent of phospholipid-associated proteins. In addition, these antibody findings were studied for associations with prothrombin degradation products, activated factor VII and activated protein C, and with the incidence of diabetic complications. The anti-phosphatidylethanolamine antibody association with proliferative retinopathy was significant.

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.

Antiphospholipid antibodies are a risk factor for early renal allograft failure

BACKGROUND

Biopsy specimens of transplanted kidneys that fail to function reveal cellular infiltrates, infarcts, and thrombi. Because antibodies to phospholipids (aPA) and/or phospholipid-binding proteins have been associated with thrombosis, we asked whether aPA are a risk factor for early allograft failure.

METHODS

Final crossmatch sera from 56 patients with primary nonfunctioning renal allografts were tested for aPA. Serum from the next consecutive patient to undergo transplantation served as transplantation controls. Both groups were compared with aPA values obtained from testing 252 control individuals. The ELISA was designed to detect IgG, IgM, and IgA antibodies to phosphatidylserine, cardiolipin, and phosphatidylethanolamine.

RESULTS

Patients were evaluated based upon the aPA ELISA findings. aPA were present in 57% of the patients with early nonfunction renal allografts and 35% of the patients with functioning grafts (P=0.0234). aPA in previously hemodialyzed patients did not predict allograft failure or success (P=0.3766). In contrast, all nonhemodialysis patients who had aPA at the time of transplantation experienced early allograft failure (P=0.0022).

CONCLUSIONS

These data show that aPA are an important risk factor for early renal allograft failure. Furthermore, aPA-positive patients who have no history of hemodialysis are at the greatest risk. Pretransplantation aPA screening of renal transplant candidates forewarns of early graft failure and indicates which patients may benefit from anticoagulant therapy.