Pregnancy loss and autoantibodies against phospholipid-binding proteins

A systematic review of the association between anti-β-2 glycoprotein I antibodies and APS manifestations

Anti-β-2 glycoprotein I antibodies (anti-B2GPI) are often cited as the major pathogenically relevant antibody in antiphospholipid syndrome (APS), but it is unclear if there is clinical evidence to support this theory. We performed a systematic review to determine if immunoglobulin G anti-B2GPI positivity was independently associated with thrombotic and/or obstetric manifestations of APS. We searched MEDLINE, EMBASE, The Cochrane Library, and clinicaltrials.gov electronic databases through April 2020 for prospective studies that met prespecified design criteria. Of 4758 articles identified through computer-assisted search, 4 studies examining obstetric outcomes and 2 studies examining thrombotic outcomes were included for qualitative assessment. The presence of anti-B2GPI had only a weak independent association with thrombosis and was, at best, inconsistently associated with obstetric complications. A quantitative assessment could not be performed because of study heterogeneity. The overall quality of the evidence was very low. Although anti-B2GPI are commonly thought to mediate APS manifestations, clinical evidence is lacking with very low-quality data to support a weak association with thrombosis.

Antiphosphatidylserine antibodies and reproductive failure

Some cases of reproductive failure with autoimmune background are characterized by the involvement of autoantibodies. This occurs mainly in patients having systemic lupus erythematosus or antiphospholipid syndrome. The autoantibodies associated with reproductive failure include: a) antibodies which directly bind phospholipid (e.g., cardiolipin, phosphatidylserine, phosphatidylethanolamine); b) antiphospholipid Abs which bind the phospholipid via phospholipid-binding glycoproteins such as b2glycoprotein-I, annexin V and prothrombin; c) autoantibodies directed to laminin-I, actin, thromboplastin, the corpus luteum, prolactin, poly (ADP-ribose), thyroglobulin and mitochondrial antibodies of the M5 type. This paper will focus on the association of antiphosphatidylserine autoantibodies and reproductive failure. Future studies are likely to help to identify peptides resembling the epitope specificities associated with the specific clinical manifestations.

The implications of autoimmunity and pregnancy

There are multiple epidemiological studies that document the potential adverse affects of autoimmunity on nearly every aspect of reproduction, even in the absence of clinically manifest autoimmune disease. Two decades ago, it was suggested that women with autoimmune diseases avoid pregnancy due to inordinate risks to the mother and the child. In contrast, newer epidemiological data demonstrated that advances in the treatment of autoimmune diseases and the management of pregnant women with these diseases have similarly improved the prognosis for mother and child. In particular, if pregnancy is planned during periods of inactive or stable disease, the result often is giving birth to healthy full-term babies without increased risks of pregnancy complications. Nonetheless, pregnancies in most autoimmune diseases are still classified as high risk because of the potential for major complications. These complications include disease exacerbations during gestation and increased perinatal mortality and morbidity in most autoimmune diseases, whereas fetal mortality is characteristic of the anti-phospholipid syndrome (APS). In this review, we will discuss these topics, including issues of hormones, along with potential long-term effects of the microchimerism phenomenon. With respect to pregnancy and autoimmune diseases, epidemiological studies have attempted to address the following questions: 1) Is it safe for the mother to become pregnant or are there acute or chronic effects of pregnancy on the course of the disease? 2) Does the disease alter the course and/or the outcome of a pregnancy and thereby represent an inordinate risk for the fetus and infant? And do new therapeutic and management approaches improve the pregnancy outcomes in women with autoimmune diseases? 3) Does passage of maternal autoantibodies represent a risk to the child? 4) Do pregnancy, parity, or other factors influencing hormonal status explain the female predominance of many autoimmune diseases, and is the pregnancy effect related to microchimerism? Answering these questions has taken on additional importance in recent decades as women in western countries now frequently choose to delay pregnancies and have some or all of their pregnancies after disease onset. In this paper, we primarily focus on APS, systemic lupus erythematosus (SLE), multiple sclerosis (MS), rheumatoid arthritis (RA), and type 1 diabetes (T1D).

Anti-beta2 glycoprotein-I antibody increases the risk of pregnancy-induced hypertension: a case-controlled study

The aim of this study was to evaluate whether anti-beta2 glycoprotein-I antibody (anti-beta2GPI) of the IgG or IgM classes is associated with the development of pregnancy-induced hypertension (PIH) or preeclampsia in the Japanese population. In a case-controlled cohort study, peripheral blood was obtained at 8-14 weeks of gestation from a consecutive series of 1155 women. The case group comprised 36 patients who later developed PIH during the pregnancy. Of the 36 PIH patients, 13 had severe PIH, 18 had preeclampsia and 11 had severe preeclampsia. One hundred and eleven age- and parity-matched women whose pregnancies ended in normal delivery without obstetric complications were selected as controls. We found that a titer of anti-beta2GPI IgG>or=1.0 U/ml was a risk factor for severe PIH (P=0.023, OR 5.7 95%CI 1.4-22.8). In addition, titers of anti-beta2GPI IgM>or=1.2 U/ml was found to be a risk factor for PIH (P=0.001, OR 8.8 95%CI 1.6-47.5). In women positive for anti-beta2GPI but negative for lupus anticoagulant, anti-cardiolipin, phosphatidylserine-dependent anti-prothrombin, or kininogen-dependent anti-phosphatidylethanolamine antibodies, the presence of anti-beta2GPI was not a significant risk factor for development of PIH or preeclampsia. In conclusion, the presence of anti-beta2GPI antibody represents a risk factor for developing PIH and severe PIH. This finding supports the utility of anti-beta2GPI determination as one of the laboratory criteria for anti-phospholipid syndrome classification. The usefulness of anti-beta2GPI measurement among women without other anti-phospholipid antibodies requires further study.

The detection of anti-β2-glycoprotein I antibodies is associated with increased risk of pregnancy loss in women with threatened abortion in the first trimester

OBJECTIVE

This study was designed to evaluate whether the detection of serum antiphospholipid autoantibodies may be useful in predicting pregnancy outcome in women with threatened abortion in the first trimester.

STUDY DESIGN

A group of 77 pregnant women of between 8 and 12 weeks' gestation with vaginal bleeding was tested for serum antiphospholipid, lupus anticoagulants, anticardiolipin, antinuclear antibodies, and anti-beta2-glycoprotein I antibodies, and was followed up until the spontaneous end of pregnancy. A control group composed of 15 healthy women with uncomplicated gestation was tested contemporarily for the same antibody panel.

RESULTS

Of the 77 patients with threatened abortion, 32 (41.5%) progressed to deliver at term and 45 (58.5%) experienced early pregnancy loss. Among the antibodies evaluated, only anti-beta2-glycoprotein I was significantly more frequent in those women whose pregnancy resulted in spontaneous abortion (22/45, 49%) than in those who progressed to term (6/32, 19%) or in the control group (2/15, 13%; p=0.004). This difference was specific to the IgM isotype (p=0.001). After adjustment by multivariate analysis, the odds ratio for pregnancy loss associated with a positive beta2-glycoprotein I antibody test was 5.18 (p=0.001).

CONCLUSION

The detection of anti-beta2-glycoprotein I antibodies is associated with an increased risk of pregnancy loss in women with threatened abortion in the first trimester.

Antibodies to β2-glycoprotein I and annexin V in women with early and late idiopathic recurrent spontaneous abortions

Anti-phospholipid antibodies (APA) are heterogeneous group of autoantibodies that target phospholipid or phospholipid-binding proteins. APAs were previously shown to induce several thrombotic states, including idiopathic recurrent spontaneous abortion (RSA). Unlike the contribution of the classical lupus anticoagulant (LAC) and anticardiolipin antibodies (ACA), the contribution of anti-beta2 glycoprotein 1 (beta2GPI) and anti-annexin V antibodies to RSA risk remain poorly understood. We assessed anti-beta2GPI and anti-annexin V IgM and IgG antibodies as RSA risk factors for RSA in 172 Tunisian women with >3 consecutive idiopathic pregnancy losses, together with 173 matched control women. The prevalence of anti-beta2GPI IgG (P=0.41, OR=1.64) and IgM (P=0.50, OR=1.70) were comparable between cases and controls. Higher anti-annexin V IgG (P=0.02, OR=5.28), but not IgM (P=0.25, OR=1.78), levels were seen in cases. Regression analysis showed that anti-beta2GPI IgM (OR=8.90; 95% CI=1.23-64.63) was associated with early RSA, while anti-annexin V IgG (OR=9.35, 95% CI=1.44-60.86) was associated with late RSA. For combined early + late RSA, the only variable selected was BMI (OR=0.93; 95% CI=0.87-0.99), and neither anti-annexin V nor anti-beta2GPI IgM and IgG were associated with early + late RSA. Anti-annexin V and anti-beta2GPI appear to be independent risk markers of RSA.

A case-control study on the association of idiopathic recurrent pregnancy loss with autoantibodies against β2-glycoprotein I and annexin V

Whereas antiphospholipid antibodies (aPL) are associated with thrombotic events and recurrent spontaneous abortion (RSA), the contribution of anti-β2 glycoprotein 1 (β2GP1) and anti-annexin V antibodies as risk factors for RSA remain poorly understood. We investigated anti-β2-GPI and anti-annexin V IgM and IgG antibodies as potential risk factors for RSA in 200 women with more than three consecutive idiopathic RSA, and 200 age-matched, healthy, parous women. Pearson’s chi squared test analysis showed that while anti-β2-GPI IgG (P= 0.416) and IgM (P= 0.72) were comparable between patients and controls, elevated anti-annexin V IgG (P= 0.006), but not IgM (P= 0.084), was more pronounced in patients. Higher frequencies of elevated IgG-only (P= 0.005), but not IgM-only (P= 1.000; OR = 6.66), anti-annexin V antibodies were noted among patients. Multinomial regression analysis showed that body-mass index (overweight and obesity;P= 0.008), education status (P< 0.001) and anti-β2-GPI IgM (P= 0.033), but not IgG (P= 0.723), were associated with early abortion, while anti-β2-GPI IgG (P= 0.030) and anti-annexin V IgG (P= 0.004) were associated with late RSA. For combined early-late RSA, the only variable selected was education status (P< 0.001), and neither anti-annexin V nor anti-β2-GPI IgM and IgG was associated with early-late RSA. Accordingly, anti-annexin V and anti-β2-GPI should be regarded as independent risk markers of RSA.

Soluble thrombomodulin levels among women with a history of recurrent pregnancy loss, with or without antiphospholipid antibodies

The endothelial cells produce substances whose elevated plasma levels acquire predictive value for the development of events. For instance, soluble thrombomodulin (sTM) levels evidence endothelial cell injury. Under specific clinical conditions the levels of sTM are raised, such as in patients with certain autoimmune disorders, pre-eclampsia or antiphospholipid syndrome. The levels of sTM, as an endothelial injury marker, were evaluated in 65 women with a history of recurrent pregnancy loss (12 with autoimmune disorders, 19 pregnant women and nine with a history of gestational hypertension or pre-eclampsia or eclampsia); 13 of them had antiphospholipid antibodies. sTM levels could be used as a predictor of pregnancy loss in future prospective studies. We compared those levels with the levels found in control groups without recurrent pregnancy loss (20 healthy women and 14 women with autoimmune disorder). There were no statistically significant differences (P = 0.729) in the levels of sTM between the recurrent pregnancy loss group (31.1 ng/ml) and the healthy control group (31.4 ng/ml) or between the different subgroups with recurrent pregnancy loss (P = 0.873) and the healthy control group or the control group with autoimmune disorder (28.0 ng/ml). There were no statistically significant differences (P = 0.605) in the levels of sTM among the patients with recurrent pregnancy loss, with or without moderate or high antiphospholipid antibodies (32.0 versus 23.3 ng/ml). Consequently, the levels of sTM would not seem to be a useful tool, as an endothelial injury marker, in women with a history of recurrent pregnancy loss with or without antiphospholipid antibodies.

HIV-1: maternal prognosis

Profound modifications in the profile of patients are currently being observed within the epidemic context of AIDS, especially with respect to pauperization and feminization of the disease. The population most frequently affected is in the reproductive age, and among adults aged 18 to 24 years, the ratio is 1 man to 1 woman, a phenomenon occurring uniformly all over the world. One of the main challenges for HIV-1-infected pregnant women and their doctors is the effect of the interaction between HIV infection and pregnancy. The present article is a review of the literature; and its objective is to assess the influence of HIV-1 infection seen from the maternal perspective, with a discussion of immunologic function, maternal prognosis, and the HIV-abortion interface. At present, we cannot conclude that pregnancy has a short-term effect on the evolution of HIV infection, but the concomitance of HIV and pregnancy may adversely affect the prognosis of gestation, especially in view of its frequent association with increased abortion and puerperal morbidity rates.

Anti-prothrombin antibodies cause thrombosis in a novel qualitative ex-vivo animal model

Anti-prothrombin antibodies (aPT) are associated with thrombotic manifestations, and their association with reproductive failure is debatable. The aim of this study was to examine whether aPT could induce thrombosis and other clinical manifestations of the anti-phospholipid syndrome (APS). Mice were immunized with either prothrombin, beta2-glycoprotein-I (beta2GPI), or beta2GPI followed by prothrombin. The presence of clinical manifestation of APS, including thrombocytopenia, lupus anticoagulant and fetal resorption rates, was evaluated in all mice groups compared with nonimmunized mice. Thrombosis was studied in a novel ex-vivo model in which the aorta was sutured for 1 min and the presence or absence of visible thrombus was qualitatively evaluated. Immunized mice developed high autoantibody levels directed towards their immunizing autoantigens. The groups immunized with beta2GPI or beta2GPI/prothrombin, but not with prothrombin alone, developed prolonged aPTT, thrombocytopenia and increased fetal resorption rate. All prothrombin-immunized mice as well as most beta2GPI/prothrombin-immunized mice developed visible thrombus within the aorta. Some beta2GPI immunized mice developed very mild thrombus. None of the CFA/PBS-injected or the nonimmunized mice developed such thrombus. Active immunization with prothrombin or beta2GPI/prothrombin is associated with prothrombotic activity of blood in an ex-vivo model. This is the first direct evidence for thrombus induction by aPT.

Antiprothrombin antibodies are associated with pregnancy loss in patients with the antiphospholipid syndrome

OBJECTIVE

To document the clinical association between the history of pregnancy loss in patients with the diagnosis of primary or secondary antiphospholipid syndrome (APS) and the presence of different antiprothrombin antibody subtypes [immunoglobulin G (IgG), IgM and IgA] in a cohort of patients with APS.

METHODS

Records of 170 female patients with primary APS, or APS secondary to systemic lupus erythematosus (SLE) or secondary to other autoimmune diseases were studied.

RESULTS

In female APS patients with IgG antiprothrombin antibodies (n = 105) significant associations to pregnancy loss (p < 0.0001), early pregnancy loss (p < 0.0001) and a negative association to thrombocytopenia (p < 0.01) could be identified. In the group of patients with IgG antiprothrombin antibodies and at least one pregnancy (n = 84) a significant association with pregnancy loss (p < 0.005) and especially with early pregnancy loss (p < 0.0001) was demonstrated. No association with other immunoglobulin subtypes of antiprothrombin antibodies could be documented. In the subgroup of patients with primary APS and at least one pregnancy in the history, pregnancy loss (p < 0.005) and early pregnancy loss (p < 0.0001) were found to be highly associated with the presence of IgG antiprothrombin antibodies. IgG antiprothrombin antibodies represent the highest independent risk factor for pregnancy loss with an odds ratio of 4.5. There was no statistically significant association with venous or arterial thrombosis in all IgG antiprothrombin antibody positive patients.

CONCLUSION

The results of this study document the association of IgG antiprothrombin antibodies with pregnancy loss and in particular early pregnancy loss in a large and well-characterized cohort of patients. We would recommend routine testing for antiprothrombin antibodies in young female patients with APS.

Anti-beta 2 glycoprotein 1 and anti-annexin V antibodies in women with recurrent miscarriage

While it has been established that anti-phospholipid antibodies (aPL) are associated with recurrent miscarriage (RM), the importance of anti-beta2 glycoprotein 1 (GP1) IgG and anti-annexin V IgG antibodies as risk factors for RM is undefined. We have investigated the prevalence of anti-beta2 GP1 IgG and anti-annexin V IgG antibodies in 54 aPL-positive and 48 aPL-negative women with RM. The prevalence of IgG anti-beta2 GP1 antibodies was not significantly different in persistently aPL-positive women with RM (7%), aPL-negative women with RM (6%) and the normal parous control group (3%). Anti-annexin V IgG antibody prevalence was significantly increased in aPL-positive women with RM compared with aPL-negative women with RM (P = 0.01). The elevations were found in 35%, 19% and 16% of aPL-positive women with RM, aPL-negative women with RM and the control group respectively. No women showed positivity for both anti-beta2 GP1 IgG and anti-annexin V antibodies. Anti-beta2 GP1 IgG antibodies do not appear to be contributory to the investigation of women with RM. Anti-annexin V antibody positivity, although associated with aPL positivity in women with RM, is not an independent risk marker.

Antiphospholipid syndrome and recurrent miscarriages

Sixty percent of recurrent spontaneous abortions are unexplained. Antiphospholipid syndrome is a multisystem disease with the predominant features of venous and arterial thrombosis, recurrent pregnancy loss, foetal death and the presence of antiphospholipid antibodies. Many epidemiological studies focus on antiphospholipid autoantibodies syndrome (APS) as a cause of recurrent spontaneous abortion (RSA). It is found that 7-25% of RSA would have APS as the main risk factor. 'Association not being synonymous with cause', the proportion of abortions due to the APS is difficult to estimate for several reasons: definition of recurrent abortion is variable, the assays for antiphospholipid antibodies are not well standardised, inclusion of patients in the study group according to the antibodies titre is author dependent. Recent studies suggest association of antiphospholipid antibodies syndrome not only with recurrent abortions but also with infertility. New mechanisms are described by which antiphospholipid antibodies could cause placental thrombosis and infarction, acting directly on the surface anticoagulant expressed on trophoblastic cells. Only lupus anticoagulant (LA) and anticardiolipin antibodies (aCL) assays are sufficiently standardised to be usable in routine. Testing for other antiphospholipid antibodies (aPLs) should remain investigational. Several treatments have been proposed: low doses of aspirin, low or immunosuppressive doses of corticosteroids, and preventive or effective dose of heparin, intravenous immunoglobulin.

Antiprothrombin autoantibodies in severe preeclampsia and abortion

PURPOSE

We examined the levels of autoantibodies against prethrombin-1 and fragment-1 in pregnant women to determine the type of autoantibodies that were associated with severe preeclampsia or spontaneous abortion.

SUBJECTS AND METHODS

We measured autoantibodies bound to prothrombin, prethrombin-1, and fragment-1 by using an enzyme-linked immunosorbent assay (ELISA) in 12 healthy nonpregnant women, 36 women with normal pregnancies, 28 pregnant women with severe preeclampsia, and 19 pregnant women who subsequently had spontaneous abortion.

RESULTS

Plasma samples in 10 (36%) of the 28 women with severe preeclampsia and 11 (58%) of the 19 women with spontaneous abortion were positive for antiprothrombin antibodies as compared with 3 (9%) of the 36 women with normal pregancies. All 11 of the positive samples from women who had spontaneous abortions were positive for antiprethrombin-1 antibody, but only 1 was positive for antifragment-1 antibody. The mean (+/- SD) titer of antiprethrombin-1 antibodies in patients with spontaneous abortion (36 +/- 9 U) was higher than that in women with normal pregnancies (10 +/- 4 U; P < 0.01). Antiprethrombin-1 antibody was detected in only 2 women with severe preeclampsia, whereas all 10 women with antiprethrombin antibodies were positive for antifragment-1 antibody. The antifragment-1 antibody titer in patients with severe preeclampsia (49 +/- 15 U) was higher than in women with normal pregnancies (13 +/- 6 U, P < 0.01).

CONCLUSIONS

There is a strong and specific association between various types of antiprothrombin antibodies with severe preeclampsia and spontaneous abortion.

Which are the best biological markers of the antiphospholipid syndrome?

The diagnosis of antiphospholipid syndrome (APS) requires the presence of both clinical and biological features. Due to the heterogeneity of anti-phospholipid antibodies (aPL) the laboratory approach for their detection includes clotting-based tests for lupus anticoagulant (LA) as well as solid-phase assays for anticardiolipin antibodies (aCL). In addition, as it has been shown that autoimmune aPL recognize epitopes on phospholipid (PL)-binding plasma proteins, assays detecting antibodies to beta 2-glycoprotein I (beta 2-GPI) or prothrombin have been developed. The association between venous or arterial thrombosis and recurrent fetal loss with the presence of conventional aPL (LA and/or aCL) has been confirmed by many studies. The LA and IgG aCL at moderate/high titre seem to exhibit the strongest association with clinical manifestations of the APS. Several reports indicate that LA is less sensitive but more specific than aCL for the APS. Assays against PLs other than CL as well as the use of mixtures of PLs have been proposed to improve the detection of APS-related aPL. Concerning antibodies to PL-binding proteins (detected in the absence of PLs), there is evidence that anti-beta 2-GPI are closely associated with thrombosis and other clinical features of the APS. Moreover, these antibodies may be more specific in the recognition of the APS and in some cases may be present in the absence of aPL detected by standard tests. Many issues are still under debate and are discussed in this review, such as the problems of standardization of anti-beta 2-GPI assays, detection of the IgA isotype of aCL and anti-beta 2-GPI, the coagulation profiles of LA in the recognition of the thrombotic risk and the association of particular markers with subsets of patients with APS.

Antiphospholipid antibodies affect trophoblast gonadotropin secretion and invasiveness by binding directly and through adhered beta2-glycoprotein I

OBJECTIVE

To investigate the in vitro ability of antiphospholipid antibodies (aPL) to bind human trophoblast cells and to affect gonadotropin secretion and invasiveness.

METHODS

Antiphospholipid antibody IgG from women with recurrent miscarriages, beta2-glycoprotein I (beta2GPI)-independent IgG aPL human monoclonal antibody (mAb) (519), and IgM anti-beta2GPI human mAb (TMIG2) were investigated for their binding to trophoblasts cultured for various amounts of time, their ability to affect invasiveness of Matrigel-coated filters, and their release of human chorionic gonadotropin (hCG).

RESULTS

Polyclonal IgG aPL, as well as mAb 519 and TMIG2, bound to trophoblasts, the highest binding being found when cells displayed the greatest amount of syncytium formation. TM1G2 binding was found to be betaGPI dependent. Both polyclonal and monoclonal aPL, but not the controls, significantly reduced hCG release and Matrigel invasiveness.

CONCLUSION

These findings suggest that aPL recognition of both anionic PL and adhered beta2GPI on trophoblast cell structures might represent a potential pathogenetic mechanism for defective placentation in women with the antiphospholipid syndrome.

Anti-beta2-glycoprotein I antibodies in women with recurrent spontaneous abortion, unexplained fetal death, and antiphospholipid syndrome

OBJECTIVE

Studies in rheumatologic and hematologic populations suggest that anti-beta(2)-glycoprotein I antibodies are more specific for the clinical manifestations of antiphospholipid syndrome than anticardiolipin antibodies. However, the association between anti-beta(2)-glycoprotein I and pregnancy loss remains uncertain. We sought to determine whether anti-beta(2)-glycoprotein I is associated with the obstetric features of antiphospholipid syndrome.

STUDY DESIGN

Sera from 4 groups of women were studied: (1) 152 healthy fertile control subjects, (2) 141 subjects with unexplained recurrent spontaneous abortions, (3) 58 subjects with unexplained fetal deaths, and (4) 73 subjects with well-characterized antiphospholipid syndrome. Serum anticardiolipin and anti-beta(2)-glycoprotein I levels were determined by enzyme-linked immunoassay.

RESULTS

Patients with antiphospholipid syndrome had significantly higher levels of immunoglobulin G and immunoglobulin M anticardiolipin and anti-beta(2)-glycoprotein I than the other 3 groups (P <.0001). However, women in the recurrent spontaneous abortion, fetal death, and fertile control groups had similar levels of each antibody. Similarly, there were no differences in the proportion of women with positive test results for each autoantibody in these 3 groups. Linear regression analysis showed significant correlation between anticardiolipin immunoglobulin G and beta(2)-glycoprotein I immunoglobulin G (R (2) = 0.544786, P =.0001) and anticardiolipin immunoglobulin M and beta(2)-glycoprotein I immunoglobulin M (R (2) = 0.525048, P =.0001).

CONCLUSION

Both anticardiolipin and anti-beta(2)-glycoprotein I are associated with antiphospholipid syndrome. However, testing for anti-beta(2)-glycoprotein I does not identify additional patients with either recurrent spontaneous abortions or unexplained fetal deaths who initially have negative test responses for anticardiolipin. This is likely because of the strong correlation between the 2 autoantibodies. Our data do not support routine testing for anti-beta(2)-glycoprotein I in addition to testing for antiphospholipid antibodies in women with recurrent pregnancy loss and unexplained fetal death.

Isotype distribution and clinical relevance of anti-beta2-glycoprotein I (beta2-GPI) antibodies: importance of IgA isotype

The aim of this study was to evaluate the prevalence of IgG, IgA and IgM anti-beta2-GPI antibodies in anti-phospholipid syndrome (APS), and to establish the clinical significance of IgA type antibodies compared with the other isotypes. Anti-beta2-GPI antibodies were measured in the sera of 70 patients by solid-phase enzyme immunoassay in gamma-irradiated polystyrene plates coated with human purified beta2-GPI. Thirty-three out of the 70 patients were classified as having APS: three of them had primary, and 30 had secondary APS related to systemic lupus erythematosus (SLE). The remaining 37 patients had SLE without APS. Anti-beta2-GPI antibodies of IgG, IgA and IgM isotypes were present in 84.8%, 59.3% and 51.5% of patients with APS. Both the frequency and the level of each isotype were significantly higher in patients with APS. This association was very strong for IgA (P = 0.0004 for the antibody frequency and P < 0.0001 for the antibody level), as well as for IgG type antibodies (P < 0.0001 and P < 0.0001), whereas it was weaker for IgM (P = 0.01 and P = 0.04). A strong relationship was demonstrated between increased IgA anti-beta2-GPI antibody levels and a history of venous thrombosis, thrombocytopenia, heart valve disease, livedo reticularis and epilepsy. IgG anti-beta2-GPI antibodies were associated with the presence of lupus anticoagulant (LA) in addition to the main features of APS. However, antibodies of IgM isotype were related only to thrombocytopenia and heart valve disease. We recommend the evaluation of anti-beta2-GPI antibodies of IgA isotype in addition to IgG in patients with clinical suspicion of APS.

Anti-prothrombin antibodies and their relation with thrombosis and lupus anticoagulant

Antiphospholipid antibodies are a heterogeneous group of antibodies, comprising antibodies with different antigen specificity. Prothrombin is one of the antigens which can be detected by antiphospholipid antibodies and therefore anti-prothrombin antibodies belong to the antiphospholipid antibody family. The presence of antiphospholipid antibodies correlates strongly with thromboembolic complications; however a mechanism by which these autoantibodies induce a thrombotic complication in vivo is not understood. The classic assays for the detection of antiphospholipid antibodies (LAC and anticardiolipin ELISAs) aim to measure all the antiphospholipid antibodies present in the samples without making a distinction between the different subspecificities of the antibodies present in one single sample. Moreover, most of the in-vitro studies performed were carried out with total IgGs, which contain a mixture of antibodies. The absence of an accurate characterization of the plasma samples and the lack of specificity of the IgGs used in in-vitro tests makes it difficult to determine the contribution of antiprothrombin antibodies to the thrombotic complications. Here we review and critically analyse the literature regarding the clinical relevance of the presence of antiprothrombin antibodies and the possible participation of these antibodies in the pathogenesis of the thrombotic complications.

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.

Antiphospholipid antibody syndrome: new insights on thrombogenic mechanisms

The antiphospholipid antibody syndrome is a thrombophilic condition manifested by vascular thrombosis or recurrent pregnancy loss together with the presence of antibodies against anionic phospholipid protein complexes. These antibodies are detected by their reactivity to the anionic phospholipids (or protein phospholipid complexes) in solid-phase immunoassays or by their property of inhibiting phospholipid-dependent coagulation reactions (the "lupus anticoagulant" effect). The pathophysiologic mechanisms of this syndrome have remained obscure because of the apparent multiplicity of antigenic determinants recognized by the antibodies and also because of the many effects which have been described for them. This article reviews current concepts of the antiphospholipid disease process and evidence for the hypothesis that thrombosis in this syndrome is a result of the displacement of annexin-V, an anionic phospholipid-binding protein with potent anticoagulant activity, from phospholipid surfaces. The authors propose that under physiologic conditions, annexin-V plays a thromboregulatory role at the vascular-blood interface by shielding anionic phospholipids from complexation with coagulation proteins in circulating blood. Thrombosis in the antiphospholipid syndrome is due to disruption of the annexin shield by antiphospholipid (and cofactor) antibodies which results in the increased exposure of thrombogenic phospholipids. Accumulated data are consistent with the hypothesis that the disruption of annexin-V binding to anionic phospholipid surfaces plays an important thrombogenic role in the antiphospholipid syndrome.

Lack of association between antiphospholipid antibodies and first-trimester spontaneous abortion: prospective study of pregnancies detected within 21 days of conception

OBJECTIVE

To determine the role of antiphospholipid antibodies and anticardiolipin antibodies in first-trimester losses, addressing experimental pitfalls that preclude excluding the possibility that these antibodies reflect merely the selection bias of studying couples only after they have already experienced losses.

DESIGN

Given that retrospective studies cannot exclude the possibility that such antibodies arise as a result of the fetal death, blood samples were obtained either before pregnancy or very early in pregnancy. Sera were obtained within 21 days of conception.

SETTING

Multicenter university-based hospitals (National Institute of Child Health and Human Development collaborative study).

PATIENT(S)

Subjects for the current study were 93 women who later experienced pregnancy loss (48 diabetic; 45 nondiabetic), matched 2:1 with 190 controls (93 diabetic and 97 nondiabetic) who subsequently had normal live-born offspring.

INTERVENTION(S)

Sera from these 283 women were analyzed for antiphospholipid antibodies by enzyme immunoassay. In 260 of the 283 women (87 with pregnancy losses; 173 with live-born infants), sera were also available to perform assays for anticardiolipin antibodies by enzyme immunoassay.

MAIN OUTCOME MEASURE(S)

Pregnancy losses.

RESULT(S)

No association was observed between pregnancy loss and the presence of antiphospholipid antibodies or anticardiolipin antibodies. Levels of antiphospholipid antibodies were 6-19 PL/mL in 62.4% of the pregnancies that ended in losses and > or = 20 PL/mL in 5.4%; among pregnancies resulting in live-born infants, the percentages were 56.8% and 6.8%, respectively. Of the pregnancies that ended in a loss, 5.7% had anticardiolipin antibodies > or = 16 GPL/mL, compared with 5.2% of those ending in a live birth.

CONCLUSION(S)

This prospective study suggests that anticardiolipin antibodies and antiphospholipid antibodies are not associated with an increased risk for first-trimester pregnancy loss.