Measurement of antiphospholipid antibody by ELISA using purified beta 2-glycoprotein I in preeclampsia.

It has been reported that the binding of some antiphospholipid antibodies (APA) to phospholipids requires the presence of beta 2-glycoprotein I (beta 2-GPI). Using a new ELISA, in which well coated phospholipids were treated with a constant amount of purified beta 2-GPI, we tried to detect the presence of APA which binds to phospholipid/beta 2-GPI complex or to phospholipids such as cardiolipin (CA) and phosphatidylserine (PS) in preeclampsia, and to check for clinical abnormalities in antibody-positive cases. Serum samples were taken from 43 cases of preeclampsia, including 26 cases of the severe type, and 47 normal pregnant women. Positive rates of anticardiolipin antibody (ACA) by ELISA using CA/beta 2-GPI complex in mild, severe and total preeclampsia were 20.0, 17.4% and 18.4% respectively. No antibody-positive cases were found in normal pregnancies. ACA was detected much more frequently when cardiolipin/beta 2-GPI complex was used in ELISA compared with ELISA without beta 2-GPI. Positive rates of antiphosphatidylserine antibody (APSA) in mild, severe and total preeclampsia were 5.9%, 11.5% and 9.3% respectively. APSA was also detected much more frequently when the phosphatidylserine/beta 2-GPI complex was used in ELISA. The frequency of intrauterine growth retardation (IUGR) in the ACA-positive subjects was higher than that of ACA negatives. We suggest that the ACA and APSA which bind to phospholipid/beta 2-GPI complex are detectable in preeclampsia, and that these antiphospholipid antibodies are related to fetal growth.     

Antiphospholipid Antibodies in Patients With Preeclampsia

PROBLEM: To determine the incidence of anticardiolipin and antiphosphatidylserine antibodies in women with preeclampsia. METHODS: Sera from 100 women with preeclampsia and 100 normotensive pregnant women in the third trimester were assayed for anticardiolipin and antiphosphatidylserine antibodies. RESULTS: Antiphosphatidylserine antibodies were positive for IgM in 1 patient (1%) and for IgG in 4 patients (4%). IgM antibodies to cardiolipin were positive in two patients (2%) while IgG antibodies to cardiolipin were positive in nine patients (9%). Only 3% of the control women were positive for antiphospholipid antibodies. None of the patients or controls had positive levels of IgA anticardiolipin or antiphosphatidylserine antibodies. CONCLUSIONS: Elevated levels of IgG or IgM antibodies to cardiolipin and phosphatidylserine were detected in 11/100 (11%) of women diagnosed with preeclampsia in the third trimester compared to only 3/100 (3%) positive in controls (P < 0.05). These findings suggest that antiphospholipid antibodies may play a pathogenic role in some women with preeclampsia.     

Affinity-purified cardiolipin-binding antibodies show heterogeneity in their binding to oxidized low-density lipoprotein

Antiphospholipid antibodies in autoimmune sera have been shown to react with a complex of phospholipids (cardiolipin) and a plasma phospholipid-binding protein, β₂-glycoprotein I (apolipoprotein H). The binding of these antibodies was inhibited by oxidized low-density lipoprotein (LDL) in sera from patients with systemic lupus erythematosus (SLE), suggesting cross-reactivity between antiphospholipid antibodies and antibodies binding to oxidized LDL. We purified antiphospholipid antibodies by cardiolipin-polyacrylamide column from seven SLE sera and studied the reactivity of eluted fractions with cardiolipin–β₂-glycoprotein I complex and oxidized LDL (malondialdehyde-conjugated LDL) in solid-phase enzyme immunoassay. In four sera the binding of IgG antibodies to cardiolipin–β₂-glycoprotein I complex and to oxidized LDL appeared in the same fractions, whereas in three sera reactivities against cardiolipin and oxidized LDL were observed, at least in part, in separate fractions. The binding to solid-phase cardiolipin was dependent on the presence of exogenous β₂-glycoprotein I in all fractions. Our findings show that antiphospholipid antibodies are heterogeneous in their binding to oxidized LDL, indicating that these two antibodies may have different subspecificities. Some eluted fractions reacted only with oxidized LDL, and did not show binding to cardiolipin–β₂-glycoprotein I complex, suggesting that the lipid part in the antigenic complex might be responsible for the cross-reactivity of these antibodies. Accordingly, the biological functions of antibodies against phospholipid–β₂-glycoprotein I complex and antibodies against oxidized LDL may also be different.     

Antiphosphatidylserine antibodies are elevated in normal tension glaucoma

The two main entities of open-angle glaucoma are primary open-angle glaucoma (POAG) and normal tension glaucoma (NTG). Both diseases may be associated with autoimmune processes. Therefore, IgG and IgM antibodies to phospholipids (APL) and their subspecies cardiolipin (ACL), phosphatidylserine (APS) and beta2-glycoprotein (beta2GP) were determined in 43 NTG patients, 40 POAG patients and 40 healthy controls in a prospective study. The most prominent observation was the increase in APS concentrations in NTG patients (IgG 20.6 +/- 2.7 U/ml, IgM 24.4 +/- 3.4 U/ml) compared with POAG patients (IgG 8.8 +/- 1.2 U/ml, IgM 11.0 +/- 1.7), and controls (IgG 7.7 +/- 1.3 U/ml, IgM 12.8 +/- 1.5 U/ml). APS may be important due to their binding specificity to phosphatidylserine molecules which become accessible during apoptosis; this in turn may lead to local thrombosis.     

Effect of Antiphospholipid Antibodies on β2Glycoprotein I-Phospholipid Interaction

PROBLEM: β₂ glycoprotein I (β₂GPI) physiologically binds to negatively charged phospholipids (PLs) and is a natural regulator of the coagulation cascade. Thrombotic clinical complications and recurrent fetal loss associated with autoimmune antiphospholipid (aPL) antibodies are thought to be related to their binding to β₂GPI-PL complex and interference with the physiological function of β₂GPI. METHOD OF STUDY: To investigate the effect of aPL on β₂GPI-PL interaction, we studied the binding of biotinylated β₂GPI to cardiolipin (CL) by enzyme-linked immunosorbent assay (ELISA) in the presence and absence of purified aPL immunoglobulin G (IgG) antibodies. RESULTS: Adding five different aPL IgG antibodies with different levels of aPL activity isolated from the sera of five patients with aPL-associated recurrent fetal death greatly increased the binding of biotinylated β₂GPI to CL-coated plates. The optical densities (ODs) were 0.635, 0.890, and 1.265 in the presence of three aPL IgG antibodies, compared to 0.425 in the absence of aPL IgG. In contrast, normal human IgG had no enhancing effect. The OD was 0.480 and 0.425, respectively. The enhancement of β₂GPI binding to CL by aPL IgG correlated with the titers of aPL antibodies. The use of phosphate-buffered saline with increasing salt concentrations as a washing buffer for the ELISA resulted in more stable binding of β₂GPI to PL in the presence of aPL IgG. CONCLUSIONS: These findings suggest that the binding of autoimmune aPL antibodies to β₂GPI-PL complex results in abnormally tighter interaction between β₂GPI and PLs, which may lead to physiological dysfunction of β₂GPI as a regulator of coagulation.     

Antiphospholipid Antibody Prevalence in Patients With IVF Failure

Antiphospholipid antibodies (APAs) have been associated with reproductive wastage. The purpose of this study was to establish the prevalence of APAs in women who have had at least 12 embryos transferred during several in vitro fertilization (IVF) cycles without ensuing pregnancy. Sera from 42 women with IVF failure and 42 women who successfully conceived after IVF were tested for the presence of APAs by ELISA. Successful post-IVF pregnancy was determined by obtaining two consecutive rising beta-hCG levels followed by an ultrasound to confirm a viable conceptus. The sera were tested for three isotypes of antibody: IgA, IgG, and IgM against seven phospholipids: cardiolipin (CL), phosphatidyle-thanolamine (PE), phosphatidylinositol (PI), phosphatidic Acid (PA), phosphatidyl-glycerol (PG), phosphatidylcholine (PC), and phosphatidyl-serine (PS). From the IVF failure group, 11/42 (26.2%) were positive for APAs. From the control group, 2/42 (4.8%) were found positive only for IgA against PE. The difference between IVF failure and successful IVF groups was significant (P=0.01). These results suggest that antiphospholipid antibodies should be considered an important marker for increased risk of IVF failure. Patients who are involved with an IVF program should be tested for the presence of APAs prior to initiation of an IVF cycle.     

Association of lupus anticoagulant with antibody against phosphatidylserine

Lupus anticoagulant (LAC) is an antiphospholipid autoantibody identified by prolongation of in vitro phospholipid-dependent coagulation tests. Its presence is associated with thromboembolic disease and recurrent pregnancy loss in patients with or without clinical autoimmune disease. The purpose of this study was to identify the specific phospholipid(s) against which LAC is directed. The sera of 15 patients with LAC and of 41 LAC-negative controls were evaluated. Specific phospholipids were used to inhibit IgG binding in a partial thromboplastin ELISA, and serologic reactivity was measured with ELISAs which used specific phospholipids in the solid phase. Both phosphatidylserine and cardiolipin significantly inhibited IgG binding in the partial thromboplastin ELISA (76 and 75%, respectively); however, the serum of one patient who was strongly positive for LAC in coagulation assays was not inhibited by cardiolipin. In the specific phospholipid ELISAs, LAC-positive sera contained IgG (15 of 15 sera) and frequently IgM (9 of 15 sera; 60%) to phosphatidylserine. Most LAC-positive sera also contained IgG antibodies against other phospholipids: cardiolipin (10 of 11 sera; 91%), phosphatidylcholine (1 of 15 sera; 7%), phosphatidylethanolamine (12 of 15 sera; 80%), phosphatidylglycerol (12 of 15 sera; 80%), and phosphatidylinositol (10 of 15 sera; 67%). None of the LAC-negative controls had measurable IgG against any of these phospholipids. We conclude that LAC-positive sera contain antibody specificities against multiple phospholipids; however, anticoagulant activity is always associated with the presence of antibodies against phosphatidylserine.     

Phospholipid Binding Plasma Proteins Required for Antiphospholipid Antibody Detection—An Overview

PROBLEM: Antibodies to phospholipid antigens (aPA) are associated with thrombosis thrombocytopenia and recurrent pregnancy loss. Contemporary data show many aPA target phospholipid-binding plasma proteins and not phospholipids. The purpose of this overview is to describe several phospholipid-binding proteins and provide data to demonstrate how the interaction between phospholipids and phospholipid binding proteins results in expression of neo-autoantigenic epitopes. METHOD: Review of existing data. RESULTS: Illustrations of how certain plasma proteins β2 glycoprotein I, prothrombin, high and low molecular weight kininogens interact with the anionic phospholipids, cardiolipin and phosphatidylserine and the zwitterionic phospholipid, phosphatidylethanolamine are shown and discussed. A model of aPA mediated thrombosis is presented. CONCLUSIONS: Some aPA recognize phospholipids directly, however, the majority and many which correlate with pathology target phospholipid binding proteins. Published data indicate that aPA represent a constellation of antibodies with multiple specificities. Insight into mechanisms responsible for aPA-associated thrombosis should provide a basis for treatment.     

Urgent Termination of Pregnancy in Pre-eclampsia and Panel of Antiphospholipid Antibodies

Problem  The present work was undertaken to investigate the occurence of autoantibodies to eight various phospholipids in time of urgent termination of the pregnancy (sectio caesarea) in patients in reproductive age with severe preeclamptic symptoms.
Method of study  Autoantibodies against annexin V, ph-serine, ph-ethanolamine, ph-inositol, ph-DL-glycerol, cardiolipin, beta2-glycoprotein I (beta2-GPI), and phosphatidic acid were studied by ELISA methods.
Results  Increased levels of IgA-beta2-glycoprotein I, IgG-beta2-glycoprotein I, IgG- anti-ph-serine, and IgG-anticardiolipin were found in sera of preeclamptic women in the time of urgent sectio caesarea when compared to the control group with physiological pregnancy.
Conclusion  Supposed increase in various antiphospholipid antibodies (aPLs) levels due to the stress during the short time of admission and a need for a quick medical decision to terminate the pregnancy was not unambiguously proven, but our results are evidently influenced by the current urgent life-saving treatment.     

Gonadotropins Do Not Induce Antiphospholipid Antibodies

PROBLEM: To determine whether the increased incidence of antiphospholipid antibodies (APAs) in women undergoing assisted reproduction might be secondary to superovulation with gonadotropins, predisposing women to an abnormal immune response and thus inducing APAs. METHOD OF STUDY: Women undergoing assisted reproduction with gonadotropins for the first time were selected and tested before the initiation of the stimulation cycle, during the cycle, and at the end of the cycle (group 1). Women who had undergone gonadotropin stimulation at least 60 days earlier (group 2) and normal, nonpregnant, fertile women (group 3) also were evaluated. Serum samples were assayed by the enzyme-linked immunosorbent assay method. RESULTS: Ten (20%) of 50 women in group 1 were positive for APAs. The 10 women who were positive for APAs remained positive throughout the treatment cycle. Positive antibodies were identified in 12 (24%) of 50 women in group 2, not significantly different from group 1 (P = 0.81). Antibodies were present in 2 of 50 normal fertile control subjects, significantly less frequently than in group 1 (P < 0.03) and in group 2 (P < 0.01). CONCLUSIONS: These data suggest that gonadotropin administration and/or the ovarian response to stimulation does not predispose women to the induction of APAs. Moreover, the incidence of APAs in this population, which is higher than that found in normal fertile women, cannot be explained by cycle-induced events.     

Interaction of Heparin With Antiphospholipid Antibodies (APA) From the Sera of Women With Recurrent Pregnancy Loss (RPL)

PROBLEM: To determine if heparin may act directly with antiphospholipid antibodies (APA) to prevent recurrent pregnancy loss (RPL). METHOD: Patients were seen at the University of Texas Southwestern Medical Center. Twenty women with a history of RPL (≥3 miscarriages), positive APA, and an otherwise normal evaluation were treated with heparin in two daily subcutaneous dosages during a successful pregnancy. APA levels were obtained prior to conception and again at 6, 20, and 30 weeks. RESULTS: Heparin reduced APA binding to cardiolipin and phosphatidylserine in a dose-dependent fashion in ELISA. Heparin affinity chromatography absorbed over 80% of the IgG anticardiolipin antibody in serum from women with high levels of APA. Women treated with increasing dosages of heparin during pregnancy had inversely decreasing levels of IgG anticardiolipin antibody. CONCLUSION: Heparin may act by directly binding APA in vivo, thereby decreasing the adverse effects of APA in women with APA associated RPL.     

Anticardiolipin Antibodies in Patients With Pregnancy Loss Induce Factor Xa Production in the Presence of (β2-Glycoprotein I

PROBLEM : Anticardiolipin antibodies (aCL) are commonly associated with recurrent pregnancy loss, though the mechanism is uncertain. Some investigators have indicated that aCL may be directed at a complex made up of cardiolipin and a blood anticoagulant, β2-glycoprotein I (β2GPI). We therefore investigated the effects of β2GPI-dependent aCL IgG enriched fractions, isolated from sera of patients with pregnancy losses, on blood coagulation. METHOD : β2GPI-dependent aCL were prepared from sera of three women with second trimester pregnancy losses, by cardiolipin affinity column chromography, following by anti-β2GPI affinity column chromatography. The effects of β2GPI and β2GPI-dependent aCL on the activation of factor X in vitro were examined. RESULTS : β2GPI inhibited the activation of factor X and β2GPI-dependent aCL blocked this inhibitory effect in a dose dependent manner. CONCLUSION : These results imply the possibility of β2GPI-dependent aCL induce hypercoagulation or thrombus by blocking the inhibitory effect of β2GPI on activation of factor X, which may result in pregnancy loss.     

IgG1 and IgG2 are the predominant subclasses of antiphospholipid antibody in women with the lupus anticoagulant

We studied the sera of 36 patients with lupus anticoagulant and IgG antibodies against both phosphatidylserine and cardiolipin. Most sera also had IgG antibodies against other phospholipids: 97% against phosphatidylinositol, 91% against phosphatidylglycerol, and 82% against phosphatidylethanolamine. IgG2 was the predominant subclass against cardiolipin and phosphatidylserine; 35 of 36 patients (98%) had IgG2 against both phospholipids. Most patients also had the IgG1 subclass; 32 of 36 (89%) against cardiolipin and 25 of 36 (69%) against phosphatidylserine. IgG3 and IgG4 subclasses were present at very low concentrations and in only a minority of the sera. The antibody response against phosphatidylserine was characterized by significantly less IgG1 than was the response against cardiolipin (P less than 0.01), although the IgG2 responses against each phospholipid were not different. IgG subclasses were unrelated to any other aspect of the patients' history, including a history of thrombocytopenia or thrombosis, a positive antinuclear antibody test, or a diagnosis of systemic lupus erythematosus.     

Anti-phospholipid antibodies and CD5+ B cells in HIV infection

This cross-sectional study evaluates the correlation between anti-phospholipid antibodies and CD5+ B cells in 110 patients infected with HIV-1. There were 89.1% of the patients who had IgG antibodies against cardiolipin and phosphatidylserine. The prevalence of IgM and IgA antibodies was < 22%. AIDS was associated with lower frequencies of IgM antibodies against cardiolipin (P = 0.05) and IgG-antibodies against cardiolipin and phosphatidylserine (P = 0.011). Drug users had higher IgM antibodies against phospholipids than patients from other risk groups (P = 0.02). A history of thromboembolic events was not accompanied by higher levels of anti-phospholipid antibodies (P > 0.2). No correlation between anti-phospholipid antibodies and CD5+ B cells was detected. Percentage part of CD5+ B lymphocytes was elevated in all patients and absolute CD4+ T lymphocyte counts and HIV p24 antigen were inversely correlated. In advanced disease a significant reduction of anti-phospholipid antibodies was contrasted with persistent elevation of CD5+ B lymphocytes. These observations may reflect immunological dysfunction involving apoptosis and endothelial damage rather than polyclonal B cell hyperstimulation. A possible explanation would be that in HIV infection an increased rate of spontaneous apoptosis in peripheral blood lymphocytes is accompanied by functional and structural changes of mitochondria. Therefore, structurally altered mitochondrial phospholipids could serve as antigen to induce specific humoral immune responses.     

Phospholipid specificity and requirement of β2-glycoprotein-I for reactivity of antibodies from patients with primary antiphospholipid syndrome

Some disease manifestations are associated with serum antiphospholipid antibodies (aPL) in patients with systemic lupus erythematosus (SLE) in what has been termed antiphospholipid syndrome (aPLS). There are patients with aPLS who do not have SLE or any other illness who have been grouped under the term primary antiphospholipid syndrome (PAPS). However, patients with diverse infections, notably syphilis, may have aPL but do not develop the associated clinical manifestations. This has been attributed, at least in part, to the immunochemical features of their aPL, including the requirement for β₂-glycoprotein-I (β₂GP-I) for binding of aPL to phospholipids, but these have not been studied in sera from patients with PAPS. By ELISA we studied 95 sera from 17 patients with PAPS and 100 sera from clinically normal individuals for IgG and IgM antibodies to the main anionic and zwitterionic phospholipids and their related compounds, phosphatidic acid (PA) and synthetic phosphorylcholine (PRC). β₂GP-I was present, either in newborn calf serum (NBCS) or purified, to block wells and to dilute samples, or was substituted by 0.3% gelatin. Inhibition studies with phospholipid micelles were used to confirm reactivities with the corresponding phospholipids. All 17 patients had IgG and 11 had IgM antibodies to cardiolipin. Antibodies to anionic phospholipids were primarily IgG whereas those to zwitterionic phospholipids were mainly, and often exclusively, IgM. We found a statistically significant difference in the mean levels of antibodies to all anionic phospholipids except aPTS, and to the haptene PA (P < 0.001) between patients and controls. The difference between levels of IgM antibodies to zwitterionic phospholipids was statistically significant with sphingomyelin (P < 0.001) and the haptene (P < 0.001). Levels of most IgG and most IgM aPL correlated significantly among them. The pattern and titers of reactivity are variable between patients, but stable within each patient. Requirement of β₂GP-I for this reactivity was not an all-or-nothing phenomenon in individual sera. In general, as in lupus sera, antibodies to anionic phospholipids require that this cofactor be present coating the ELISA plates, whereas those to zwitterionic phospholipids do not.It would appear that patients with PAPS have polyclonal mixtures of antibodies that react with various phospholipids and have different requirements for β₂GP-I for such reactivity.     

The effect of phospholipids on the formation of immune complexes between autoantibodies and beta2-glycoprotein I or prothrombin

In the last decennium, it became clear that antiphospholipid antibodies found in patients with antiphospholipid syndrome (APS) are in fact antibodies against lipid-bound plasma proteins. The most frequently occurring antigens are beta2-glycoprotein I and prothrombin, although several other lipid-bound plasma proteins have been reported as antigen for antiphospholipid antibodies. Both proteins bind to anionic phospholipids, mainly phosphatidylserine, which becomes exposed at the surface of activated platelets, apoptotic cells, or cell-derived microparticles. The binding of beta2-glycoprotein I and prothrombin to these cell surfaces or to artificial lipid vesicles with comparable amounts of anionic phospholipids is rather weak. Antiphospholipid antibodies from patients are predominantly of low affinity regarding their interaction with beta2-glycoprotein I or prothrombin in solution. In the presence of a suitable phospholipid surface, however, this interaction is strongly enhanced. There is now strong evidence that formation of bivalent, trimolecular immune complexes at the lipid membrane essentially contributes to the binding of these intrinsically low affinity patient antibodies. Depending on the affinity, the epitope specificity, and the polyclonality of a particular IgG preparation, multimeric structures of lipid-bound immune complexes may form a lattice with multiple interactions on the lipid (cell) surface. It is hypothesized that the functional activity, that is, the ability of antibodies to interfere with lipid-dependent reactions, not only depends on their affinity for the antigen, but also on their ability to form multiple interconnected bivalent trimolecular complexes at the lipid (or cell) surface. It is further proposed that the rate of desorption of immune complexes may present a better indicator for the functional properties of the antibodies than the amount of adsorbed immune complexes.     

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.     

Hidden anti-phospholipid antibodies in normal human sera circulate as immune complexes whose antigen can be removed by heat,acid, hypermolar buffers or phospholipase treatments

Heat treatment of normal human serum reveals otherwise masked anti-cardiolipin antibodies (aCL). We studied the mechanism of masking and the nature of the inhibitor of these aCL IgG. Other forms of treatment, besides heating for 30 min at 56 °C, can also unmask hidden aCL IgG. These include acid pH, hypermolar buffers and phospholipase digestion. When unmasked, these aCL recognize other anionic and zwitterionic phospholipids, but do not react with DNA, cell antigens or IgG. Using thin layer chromatography we demonstrate that the heat-labile inhibitor(s) of these aCL are phosphatidylserine, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine. These antibodies are not β₂ -glycoprotein-I dependent and actually compete with this protein for phospholipid binding. The hidden antibodies are comprised of two populations of IgG autoantibodies: one reactive with cardiolipin, phosphatidylserine, phosphatidylinositol, phosphatidylglycerol, phosphatidylethanolamine and sphingomyelin, and the other reactive almost exclusively with phosphatidylcholine and phosphorylcholine on enzyme-linked immunosorbent assay plates or when exposed by bromelain on the erythrocyte surface. Our data suggest that hidden aCL are natural oligoreactive IgG anti-phospholipid autoantibodies that circulate masked by their antigen.     

The Selective Use of Heparin/Aspirin Therapy,Alone or in Combination with Intravenous Immunoglobulin G,in the Management of Antiphospholipid Antibody-Positive Women Undergoing In Vitro Fertilization

PROBLEM: The effect of mini-dose heparin/aspirin (H/A) alone vs. combined intravenous immunoglobulin G (IVIg) and H/A on in vitro fertilization (IVF) birthrates in women who test seropositive for antiphospholipid antibodies (APA+) was evaluated, as was the question of whether outcome is influenced by the gammaglobulin isotype(s) or the phospholipid (PL) epitope(s) to which the APAs are directed. METHOD OF STUDY : A case-control study was conducted in three phases, spanning a 4-year period, in a multicenter clinical research environment. Six hundred eighty-seven APA+ women, who were younger than 40 years and who each, completed up to three consecutive IVF/embryo transfer cycles within a 12-month period, were given either H/A alone or H/A in combination with IVIg. Birthrates relative to the type of immunotherapy (i.e., H/A alone and H/A with IVIg) and APA profile were the main outcome measurements. RESULTS: In phase I, 687 women who tested APA+ to one or more PL epitopes underwent two or fewer IVF attempts for a total of 1050 IVF cycles. Four hundred seventy-seven (46%) births occurred in 923 IVF cycles in which H/A alone was administered. Twenty-two (17%) births occurred after 127 IVF cycles in which H/A was not administered. In phase II, 322 of 687 women tested positive for a single APA subtype. These subjects underwent up to two consecutive IVF attempts for a total of 521 IVF cycles while receiving H/A alone. The birthrate was significantly lower for women whose APAs were directed toward phosphatidylethanolamine (PE) or phosphatidylserine (PS) involving IgG or IgM isotypes than for women who had any other APA (17% vs. 43%). In phase III, 121 women who did not achieve live births after two consecutive IVF attempts in which H/A alone was administered received IVIg in combination with H/A during their third consecutive IVF cycle. The birth rate was 41% after these IVF cycles when anti-PS or anti-PE involving IgG or IgM isotypes were present, as compared with 17% when H/A alone was administered. The IVF outcome did not improve when IVIg was administered in association with any other single APA. CONCLUSIONS: The treatment of APA+ women with H/A alone improves IVF birthrates. This benefit is selective in that it does not apply in cases in which IgG- or IgM-related APAs are directed against PE or PS. In such cases, the addition of IVIg significantly improves the outcome.     

Reactivity patterns of human anticardiolipin and other antiphospholipid antibodies in syphilitic sera.

Sera from patients with proven cases of syphilis were tested for the presence of antibodies to structurally important phospholipids by using qualitative and quantitative assays. All 47 sera examined qualitatively contained antibodies to cardiolipin, phosphatidic acid, and phosphatidylserine, but not antibodies to other selected phospholipids. Such reactivity was not found in normal (Red Cross) sera. Although the degree of antibody binding to phospholipids varied in individual sera, reactivity was almost always greater with cardiolipin than with phosphatidic acid or phosphatidylserine. Binding saturability was found in sera as the cardiolipin concentration was increased over a constant area of nitrocellulose paper. Anti-cardiolipin binding measured by the protein A method gave results similar to the results measured by using anti-immunoglobulin G, which supports the conclusion that binding was to the Fab portion of the immunoglobulin molecule. When measured as a function of serum concentration and plotted in double-reciprocal fashion, the anti-cardiolipin binding data for two syphilitic sera had similar Kd values but different Bmax values. Stoichiometric calculations indicated that approximately 11,000 to 16,000 mol of cardiolipin appeared to be bound per mole of labeled second antibody. These observations may mean that the anti-cardiolipin antibody does not recognize the individual cardiolipin molecule as the antigenic site but recognizes some structural form of the phospholipid or that steric hindrance related to the interaction of the phospholipid with nitrocellulose paper prevented the bulk of cardiolipin molecules from reaching. The structural specificity of the antibodies identified excludes the possibility that these antibodies are directed against the phosphodiester linkage. These findings should give impetus to future study of a potential pathogenic or marker role for these antibodies in syphilis and in other syndromes in which membrane damage may be a primary event.