Immunology of the antiphospholipid antibody syndrome

Association between anti-nucleophosmin and anti-cardiolipin antibodies in (NZW x BXSB)F1 mice and human systemic lupus erythematosus

We showed previously that nucleophosmin (NPM), a nucleolar phosphoprotein, is recognized by sera from (NZW x BXSB)F1 (WB) mice, a model of systemic lupus erythematosus (SLE) and anti-phospholipid syndrome. In the present study we analysed the prevalence and kinetics of anti-NPM autoantibodies in WB mice by a solid-phase ELISA with recombinant human (rh) NPM as the antigen and showed that most male WB mouse sera had anti-NPM antibodies that were responsible for their indirect immunofluorescence staining pattern on Hep-2 cells. Anti-NPM antibodies were significantly associated with anti-cardiolipin (aCL) antibodies. This antibody profile mirrored that observed in certain human SLE sera because anti-NPM antibodies were detected in 28% of the sera from patients with SLE and were similarly associated with aCL antibodies. The demonstration that rhNPM bound to cardiolipin (CL) in vitro and increased the CL-binding activity of a WB-derived aCL monoclonal antibody indicates that NPM can interact with CL to form SLE-related immunogenic particles that might be responsible for the concomitant production of anti-NPM and aCL antibodies.

Antigenic structures recognized by anti-β2-glycoprotein I auto-antibodies

Beta2-glycoprotein I (beta2-GPI) is a major antigen for anti-cardiolipin antibodies and their epitopes are cryptic. Conformation of each domain of beta2-GPI was optimized from its crystal structure by energy minimization and by molecular dynamics simulation. Three electrostatic interactions, i.e. D193-K246, D222-K317 and E228-K308, were observed between domains IV and V in the optimized structure that was constructed based on the consensus sequences obtained by the phage-displayed random peptide library. Antigenic structures determined by the epitope mapping mainly consisted of hydrophobic amino acids located on two discontinuous sequences in domain IV. These amino acid clusters, as an epitope, were covered by domain V and were of a hidden nature. A similar but incomplete counterpart to the epitopic clusters was found in domain I but was not in domains II or III. Binding of anti-beta2-GPI auto-antibodies to solid-phase beta2-GPI was significantly reduced either by L replacement for W235, a common amino acid component for the epitopes, or by V replacement for all of D193, D222 and E228. Structural analysis indicated a hypothesis that these electrostatic interactions between domains IV and V retained exposure to W235 and that epitope spreading occurred in the region surrounding W235. Thus, epitopic structures recognized by anti-beta2-GPI auto-antibodies are cryptic and inter-domain electrostatic interactions are involved in their in exposure.

Leprosy & gangrene: a rare association; role of anti phospholipid antibodies

BACKGROUND

Leprosy still remains an important public health problem for many parts of the world. An association of gangrene with leprosy is a rare one & can have a number of causative mechanisms. We present a case with Leprosy & gangrene with positive anti phopholipid antibody titers.

CASE PRESENTATION

A 50-year-old non-diabetic, non-hypertensive lady presented with 2 months history of progressive gangrene of bilateral toes. She was found to have madarosis & hypopigmented, hypoaesthetic macular lesions on the upper limb & thighs. Bilateral ulnar & popliteal nerves were thickened. A skin biopsy of the lesions revealed borderline tuberculoid leprosy, slit skin smears revealed a bacteriological index of 1+. She did not have any evidence of thromboembolic episode or atherosclerosis. ACLA was positive at presentation & also on another occasion 6 weeks later. ACLAs were of the IgM type on both occasions. Lupus Anticoagulant & beta2 GPI antibody were negative. DOPPLER of the lower limb arteries did not reveal any abnormality. Patient was successfully treated with multi-drug antileprotics & anticoagulants.

CONCLUSION

Infectious APLAs should be recognized as a cause of thrombosis in Leprosy. Appropriate anticoagulation can salvage limb function.

The spectrum of differential diagnosis in neurological patients with livedo reticularis and livedo racemosa. A literature review

Livedo is a cutaneous sign of striking violaceous netlike patterned erythema of the skin. This dermatological phenomenon is of special interest in the differential diagnosis in neurological patients. In 1907 Ehrmann distinguished two different patterns of livedo: the pathological livedo racemosa and the physiological livedo reticularis. Despite important clinical differences, in the English language literature the heading livedo reticularis is still used for all types of livedo. A literature review about the spectrum of differential diagnosis in patients with livedo reticularis (especially cutis marmorata and amantadine-induced livedo reticularis) and livedo racemosa (especially Sneddon's syndrome, Divry-van Bogaert syndrome, systemic lupus erythematosus, antiphospholipid antibody syndrome, polyarteritis nodosa, cholesterol embolization syndrome, livedoid vasculopathy and haematological diseases) is provided.

Anti-Phospholipid Antibodies against Phosphatidylinositol, and Phosphatidylserine are More Significant in Reproductive Failure than Antibodies against Cardiolipin only

PROBLEM

The humoral immune response to phospholipids was investigated in women with reproductive failure [1073 women after one in vitro fertilization (IVF), 853 women after two and more IVF, 627 women after three and more repeated spontaneous miscarriages or missed abortions, 412 women after diagnostic laparoscopy] and compared with that of 391 healthy fertile women.

METHOD OF STUDY

Sera from all women in the study were tested by enzyme-linked immunosorbent assay (ELISA) for the detection of IgG, IgA, and IgM isotypes of antibodies against seven phospholipids (aPLs), i.e. cardiolipin, L-phosphatidylserine, phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, phosphatidylacid as well as against beta2-glycoprotein I.

RESULTS

Patients after two and more IVF (48 and 50%, respectively), patients with three and more repeated spontaneous miscarriages (50 and 46.5%, respectively) are associated with significantly higher serum levels of aPLs against inositol, and L-serine (P < 0.01). A quarter of them were positive for three and more aPLs.

CONCLUSION

It seems that determination of aPLs only against cardiolipin in reproductive failure is not sufficient for obstetric-gynecology diagnosis as the primary anti-phospholipid syndrome. Our long-ranging study (from 1998 to 2003) shows the necessity to test for a complete aPLs profile. Sera from patients after two and more IVF procedures, and sera from women after three and more repeated abortions are immunologically more active than sera from women after one unsuccessful IVF and sera from women after diagnostic laparoscopy. This important result is very significant for future treatment.

Ethnic and geographical variation in antiphospholipid (Hughes) syndrome

Investigation of the clinical epidemiology of the antiphospholipid syndrome (APS) is in its early stages. During the past 20 years, studies of antiphospholipid antibodies (aPL) and APS have been made in many countries and ethno-geographical groups. aPL appear to occur in all populations studied, with some variations noted in their frequency and in the clinical complications. Environmental and genetic factors contribute to ethnic variation and susceptibility to APS and thus inter-ethnic differences in disease patterns may be due to environmental or genetic factors, or both.

Antiphospholipid syndrome in patients with systemic lupus erythematosus treated by autologous hematopoietic stem cell transplantation

Systemic lupus erythematosus (SLE) is the most common disease associated with antiphospholipid syndrome (APS). We, therefore, evaluated 46 patients with refractory SLE treated by autologous hematopoietic stem cell transplantation (HSCT) for a history of APS prior to transplantation. The prevalence of SLE-related APS in our patient population was 61% (28 of 46 patients with refractory SLE). Nineteen of 28 patients with APS had lupus anticoagulant (LA) or high titers of anticardiolipin antibodies (ACLAs), either immunoglobulin (Ig)G or IgM, when evaluated at study entry. Six of 8 evaluable LA+ patients became and remained LA-; 5 of 7 initially ACLA IgG+ patients and 9 of 11 ACLA IgM+ patients demonstrated normalization of ACLA titers when followed after HSCT. Eighteen of 22 patients refractory to chronic anticoagulation discontinued anticoagulation therapy a median of 4 months after transplantation; 78% of them remained free of thrombotic events and in complete SLE remission for up to 78 months (median, 15 months) after HSCT. There was no treatment-related mortality. Autologous HSCT may be performed safely in patients with APS and appears to be effective therapy for eliminating ALPAs and preventing thrombotic complications in patients with SLE.

Anti-phospholipid antibodies (aPL) and apoptosis: prothrombin-dependent aPL as a paradigm for phospholipid-dependent interactions with apoptotic cells

The natural targets of anti-phospholipid antibodies (aPL) and the stimuli that induce them remain unknown. Apoptotic cells have been proposed as both potential targets and immunogens for anti-phospholipid antibodies. Demonstration of selective recognition by anti-phospholipid antibodies provides support for apoptotic cells as antigenic targets. Here, we summarize data showing that prothrombin (PT) binds to apoptotic, but not viable, cells, and that apoptotic-cell bound prothrombin provides a target for human polyclonal and murine monoclonal lupus anticoagulant (LA) antibodies. We discuss findings for two monoclonal lupus anticoagulant antibodies that have high (antibody 29J3-62) or low (antibody 29I4-24) affinity, respectively, for soluble prothrombin. Despite their very different affinities for soluble prothrombin, both monoclonal antibodies reacted similarly with prothrombin bound to phospholipid or apoptotic cells. Furthermore, both antibodies enhanced the binding of prothrombin to apoptotic cells. We propose that the recognition of apoptotic cells by these prothrombin-dependent monoclonal antibodies provides a paradigm for other anti-phospholipid autoantibodies. 29I4-24 is prototypical of phospholipid-dependent anti-phospholipid antibodies, while 29J3-62 represents a prototype for phospholipid-independent anti-phospholipid antibodies. Proteins such as prothrombin and beta2-glycoprotein I (beta2GPI) bind to apoptotic cells, thereby enhancing the recognition of apoptotic cells by anti-phospholipid antibodies. Furthermore, anti-phospholipid antibodies potentiate the interaction of these proteins with apoptotic cells. While it is unclear whether apoptotic cells are the inducing stimuli in patients with anti-phospholipid antibodies or even whether anti-phospholipid antibodies interact with apoptotic cells in vivo, it is nonetheless clear that anti-phospholipid antibodies have the potential to affect both the procoagulant activity and the uptake and clearance of apoptotic cells.

Beta-2-glycoprotein specificity of human anti-phospholipid antibody resides on the light chain: a novel mechanism for acquisition of cross-reactivity by an autoantibody

We have recently shown that the anti-cardiolipin activity of human anti-phospholipid antibody UK4 (lambda) resides on its heavy chain. We now show that UK4 possesses strong reactivity to the plasma-protein beta2-Glycoprotein I (beta2-GPI) also. Utilizing chain shuffling experiments involving an unrelated anti-p185 antibody 4D5 (kappa) with no reactivity to beta2-GPI, we now demonstrate that both the constructs possessing the auto-antibody-derived light chain exhibited significant binding to beta2-GPI. However, the construct possessing UK4 heavy chain in association with 4D5 light chain, exhibited no anti-beta2-GPI activity. Furthermore, there was a low increase (approximately 10%) in the binding of UK4 to cardiolipin in the presence of beta2-GPI. The results demonstrate that anti-beta2-GPI activity resides on UK4 light chain and, importantly, this activity could be transferred to a novel antibody construct via the light chain alone. Computer-generated models of the three-dimensional structures of UK4 and its hybrids, suggest predominant interaction of UK4 light chain with domain IV of beta2-GPI. Molecular docking experiments highlight a number of potential sites on beta2-GPI for interaction of UK4 and indicate as to how beta2-GPI recognition may occur primarily via the autoantibody light chain. The study provides first demonstration of the occurrence of anti-phospholipid and anti-beta2-GPI activities separately on heavy and light chains of an autoantibody. The possible mechanisms that such antibodies may employ to recognise their antigens, are discussed.

High avidity anti-beta 2-glycoprotein I antibodies in patients with antiphospholipid syndrome

OBJECTIVE

To evaluate avidity of IgG anti-beta 2-glycoprotein I antibodies (anti-beta2-GPI) in patients with antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE) in relation to thrombosis, and to demonstrate a possible affinity maturation of IgG anti-beta 2-GPI during the disease course.

METHODS

64 sera from 32 patients (18 with primary or secondary APS, 14 with SLE without APS) and their respective IgG fractions or affinity purified anti-beta 2-GPI were studied by anticardiolipin (aCL) and anti-beta 2-GPI enzyme linked immunosorbent assay and by chaotropic assay.

RESULTS

Six, 12, and 14 patients had high, low, and heterogeneous avidity IgG anti-beta 2-GPI, respectively. In 12 patients an increase in antibody avidity was observed over a period of between four and 12 years. More patients with APS were in the high avidity than in the low avidity anti-beta 2-GPI group, while the opposite was observed for SLE alone (both p<0.05). The most common clinical feature among patients with high avidity anti-beta 2-GPI was thrombosis, mainly venous thrombosis (p<0.05 and p<0.02, respectively, v the low avidity anti-beta 2-GPI group).

CONCLUSIONS

Patients with APS with or without SLE may have anti-beta2-GPI of high, low, or heterogeneous avidity. High avidity anti-beta 2-GPI appear to be associated with thrombosis and APS, while in pure SLE low avidity anti-beta 2-GPI may prevail. Monitoring of avidity may help elucidate the role of anti-beta 2-GPI affinity maturation in the pathogenesis of APS.

Combined search for anti–β2-glycoprotein i and anticardiolipin antibodies in antiphospholipid syndrome: Contribution to diagnosis

In this study we sought to assess (1) the diagnostic value of a combined search for anti-beta(2)-glycoprotein (abeta(2)-GPIs) and anticardiolipin antibodies (aCLs) in primary (APS I) and secondary (APS II) antiphospholipid syndrome and (2) the influence of the beta(2)-GPI preparation in the ELISA's results. abeta(2)-GPI and aCL concentrations were assessed in 70 patients with APS and compared with those in 65 patients with systemic lupus erythematosus (SLE) without clinical features of APS. In APS patients (38 with APS I, 32 with APS II), the diagnosis had to have been made at least 3 years earlier; in subjects with SLE, the diagnosis had to have been made at least 5 years earlier. All serum samples were tested for abeta(2) -GPI with the use of an in-house ELISA with an abeta(2) -GPI preparation from human plasma. Samples negative for abeta(2) -GPI were controlled with 2 additional beta(2)-GPI preparations, 1 from human serum and 1 from bovine serum. In APS, abeta(2)-GPIs were more frequent than in SLE (76% and 15%, respectively; P <.0001), mainly with IgG isotype and with significantly higher levels than those found in SLE. The specificity for APS was 92% for IgG abeta(2)-GPIs and 68% for IgG aCLs. The highest association with APS was found for the combination of the 2 markers (odds ratio 29; 95% confidence interval 10-76; P <.0001). Among the APS patients, 6 were positive for aCL only and remained negative regardless of which beta 2 -GPI preparation was used; 1 patient was aCL-negative and only positive with human beta 2 -GPI. These data emphasize the heterogeneity of the APS immunologic profile and the diagnostic possibilities of both antibodies.

HIV infection and antiphospholipid antibody: literature review and link to the antiphospholipid syndrome

There is a high incidence of antiphospholipid antibodies, detected by assays for anticardiolipin or lupus-like anticoagulant, in HIV disease. However, a link to the antiphospholipid syndrome, with clinical thrombosis, is tenuous. We report a case of a 25-year-old man with undetermined risk factors for HIV presenting with possible antiphospholipid syndrome manifesting as necrotic skin lesions as the initial clinical presentation for HIV. We also review the literature exploring the association between HIV and antiphospholipid syndrome.

Thrombotic disease in systemic lupus erythematosus is associated with a maintained systemic platelet activation

Patients with systemic lupus erythematosus (SLE) have an increased risk of thrombosis. Platelet-induced extracellular phosphorylation of plasma proteins suggests that this is due to persistent activation of the platelets. We examined 30 SLE patients (15 with thrombotic disease), 18 non-SLE patients with deep vein thrombosis (DVT) and 50 healthy controls by analysing beta-thromboglobulin, activated factor XI-antithrombin complexes and fibrinogen-bound phosphate. All parameters were elevated in SLE patients, particularly those with thrombosis, but normal in DVT cases and healthy controls. We conclude that thrombotic disease in SLE patients is associated with a persistent systemic platelet activation that may lower the threshold for induction of thrombosis.

A two-step coagulation test to identify antibeta-glycoprotein I lupus anticoagulants

Lupus anticoagulants (LA) are immunoglobulins which inhibit phospholipid (PL)-dependent coagulation tests. LA are not specific, as they may reflect the presence of antibodies to human prothrombin, human beta(2)-Glycoprotein I (beta(2)GPI), an association of previous antibodies or other antibodies. Antibodies to human beta(2)GPI act as in vitro anticoagulants by enhancing the binding of beta(2)GPI to PL, and this binding may be influenced by calcium ion concentration. A reduction in final calcium concentration, from 10 mm to 5 mm, increased coagulation times in both dilute Russell Viper Venom Time (dRVVT) and dilute Prothrombin Time (dPT) when plasmas of patients with antibeta(2)GPI antibodies were used. Ten LA patients showed increased dRVVT and dPT ratios from means of 1.5 to 1.7 (P < 0.001) and 2.4 to 4.3 (P = 0.002), respectively. Instead, all LA-positive antibeta(2)GPI antibody-negative patients showed decreased coagulation times from mean ratios of 1.5 to 1.3 (P = 0.004) in dRVVT and from 2.0 to 1.5 (P = 0.01) in dPT. These results are confirmed by running dRVVT of normal plasma spiked with affinity purified IgG antibeta(2)GPI antibodies. Therefore, when a PL-dependent coagulation test is run twice, at different final calcium concentrations, antibeta(2)GPI LA can be identified.

Anticardiolipin, anti-beta(2)-glycoprotein I and antiprothrombin antibodies in black South African patients with infectious disease

OBJECTIVES

To investigate IgG, IgM, and IgA, antiphospholipid antibodies (aPL), against cardiolipin (aCL), beta(2)-glycoprotein I (anti-beta(2)GPI), and prothrombin (anti-PT), in black South African patients with infectious disease. Unlike patients with systemic lupus erythematosus (SLE) and the antiphospholipid syndrome (APS), raised levels of aPL in infectious diseases are not usually associated with thrombotic complications.

PATIENTS AND METHODS

Serum samples from 272 patients with a variety of infectious diseases (100 HIV positive, 112 leprosy, 25 syphilis, 25 malaria, and 10 HCV patients) were studied and compared with autoantibody levels in 100 normal controls. All three aPL were measured using commercial enzyme linked immunosorbent assay (ELISA) kits.

RESULTS

Raised levels of all three aPL were found in all patient groups studied: aCL in 7%, anti-beta(2)GPI in 6%, and aPT in 43% of 100 HIV patients, in 29%, 89%, and 21% of 112 patients with leprosy, in 8%, 8%, and 28% of 25 patients with syphilis, in 12%, 8%, and 28% of 25 patients with malaria, and in 20%, 30%, and 30% of 10 HCV patients studied, respectively.

CONCLUSIONS

The prevalence of aCL and anti-beta(2)GPI in black South African HIV positive patients, or those with syphilis, malaria, or hepatitis C virus is lower than reported for mixed race or white populations. aPT were the most prevalent aPL detected in these patient groups, except in patients with leprosy, for whom anti-beta(2)GPI was the most prevalent, and where the spectrum of aPL was similar to that seen in patients with SLE and APS.

Anti-cardiolipin/beta-2 glycoprotein activities co-exist on human anti-DNA antibody light chains

We have recently shown that the human anti-DNA antibodies B3 and 33H11 also bind cardiolipin and that the anti-autoantigen activity resides predominantly on their lambda light chains. We now show that the two auto-antibodies possess strong reactivity to the plasma-protein 2-Glycoprotein I (beta2-GPI) also. Utilizing chain shuffling experiments involving an unrelated anti-p185 antibody 4D5 with insignificant reactivity to cardiolipin or to beta2-GPI, we now demonstrate that hybrid Fabs with constituent light chain, but not the heavy chain, of B3 or 33H11, exhibit anti-cardiolipin activity. Furthermore, the constructs possessing the auto-antibody-derived light chain also exhibited significant reactivity to beta2-GPI. The results suggest that anti-DNA, anti-cardiolipin and anti-beta2-GPI activities co-exist on the light chains of the antibodies studied and, importantly, these activities could be transferred to antibody constructs by their light chains alone. Computer-generated models of the three-dimensional structures of the auto-antibodies and their hybrids, suggest predominant interaction of their light chains with domain IV of beta2-GPI.

High prevalence of antiphospholipid antibodies in Asian cancer patients with thrombosis

Thrombotic complications are a significant cause of morbidity and mortality in cancer patients. Studies in Caucasian populations have shown that up to one-third of such patients test positive to antiphospholipid antibodies. Our aim was to determine the prevalence and serotypes of antiphospholipid antibodies in an unselected group of Asian cancer patients with thrombosis. All patients with cancer-related thrombosis seen in the Department of Hematology-Oncology and Radiation Oncology were enrolled in this study. The study period was from April 2000 to May 2001. Antiphospholipid antibodies tests were performed, namely lupus anticoagulant screen, anticardiolipin antibodies (IgG and IgM) and anti-beta-2 glycoprotein I antibodies (B2 GPI) IgG, IgM and IgA. Thirty-three patients were recruited. There were 14 males and 19 females, with an age range of 35-78 years of age. Of those enrolled, there were 25 Chinese, five Malays and three Indians. The patients had several cancer types: 11 (36.7%) patients had adenocarcinoma as the histological cell type. Of the 33 patients, 75.8% had stage IV disease. Arterial thrombosis was seen in eight patients (24.2%), and venous thrombosis occurred in 29 patients (87.9%). Antiphospholipid antibodies were positive in 60.6% of the patients, of which anti-B2GPI IgA antibody was the most prevalent antiphospholipid present (46.9%). The presence of anti-beta-2 glycoprotein I IgA antibody was associated with strokes, extensive and recurrent venous thrombosis, and coincident arterial and venous thrombosis. A high prevalence of antiphospholipid antibodies (60.6%) was found in Asian patients with cancer-related thrombosis. The presence of antiphospholipid antibodies, particularly anti B2GPI IgA, may identify a subset of cancer patients who are at high risk of developing thrombotic complications, and further studies are warranted.

Anti-beta2-glycoprotein I antibodies and ischemic stroke in a 20-month-old boy

Antibodies to beta2-glycoprotein I (anti-beta2GPI) have been associated with recurrent thrombosis and pregnancy morbidity. However, the prevalence of anti-beta2GPI in children suffering from cerebral infarction is unknown. We report on a 20-month-old boy who had an ischemic stroke, secondary to antiphospholipid syndrome with high titers of immunoglobulin G anti-beta2GPI (first titer: 132 U; second titer 6 weeks later: 350 U; normal range: 0-100 U). Anticardiolipin antibodies and lupus anticoagulant tests were negative. All other causes of infarction were excluded. Laboratory studies showed anti-beta2GPI IgG levels of 164 U and 216 U at 6 months and 2 years, respectively, after the onset. The patient received treatment with low-dose aspirin. To our knowledge, this is the first reported case of childhood ischemic stroke with only anti-beta2GPI but no antibodies detectable in standard antiphospholipid assays. This case supports the recommendation of others to search for these antibodies in the presence of strong clinical suspicion of antiphospholipid syndrome, when anticardiolipin antibodies and lupus anticoagulant tests are negative.

Evaluation of clinical and laboratory features of antiphospholipid syndrome: a retrospective study of 637 patients

We retrospectively analysed the data of 1519 antiphospholipid antibody (APLA) positive patients between 1986 and 1999. Among them 637 were considered to have antiphospholipid syndrome (APS) based on the 1999 preliminary classification criteria, while 704 patients had no clinical signs of the syndrome. Our aim was to compare the autoantibody profile and clinical characteristics of primary and secondary APS, moreover to evaluate the associations between different APLA and specific symptoms attributable to APS. In our results, the APLA profiles for primary and SLE-associated secondary APS were similar. Among the evaluated clinical symptoms, cerebrovascular thrombosis was found to be more frequent in the SLE-associated, than in the primary APS group (P = 0.04). We identified important differences in the clinical profile of patient populations with various types of APLA. Venous thrombosis occurred more frequently in subjects withlupus anticoagulant (LA), than in those with IgG or IgM type ACLA (P < 0.0001), while coronary, carotid and peripheral artery thrombosis occurred more often in subjects with IgG or IgM ACLA (P < 0.0001). These findings may support the role of antibodies to cardiolipin or its cofactor, beta2glycoprotein I (beta2-GPI) in the initiation and progression of atherosclerosis. Cerebrovascular thrombosis was detected in larger proportion of LA or IgG ACLA-positive patients compared with to IgM ACLA-positive subjects, while the occurrence of foetal loss was similar in all three groups.

[Antiphospholipid antibodies in HELLP syndrome: clinical and biological study in 68 women]

PURPOSE

Pregnancy complicated by the HELLP syndrome and antiphospholipid syndrome have rarely been reported. We report a study on anticardiolipin antibodies in HELLP syndrome.

METHODS

Between March 1996 and September 1999, anticardiolipin antibodies were checked in all women with HELLP syndrome hospitalised in a maternity of the North of France. The women with positive anticardiolipin antibodies were seen month later in a internal medicine department.

RESULTS

In the period 68 women with HELLP syndrome were checked for anticardiolipin antibodies. Apl were present in 9 patients (Incidence 42.8/1000 HELLP Year). They persisted after the accident only in 3 patients. Antiphospholipid syndrome was diagnosed in 2 patients, prevalence between the HELLP syndrome for the 42 month period was 0.03.

CONCLUSIONS

HELLP syndrome may be a manifestation linked to the antiphospholipid syndrome and may revealed it.

Clinical and laboratory evaluation of thrombophilia

Thrombophilia is the predisposition to venous thromboembolism and is caused by inherited and acquired factors, alone or in combination. With the discovery of APC resistance and the prothrombin gene mutation, more than half of all patients with clinical characteristics of thrombophilia are now diagnosed with an inherited disorder. The hypercoagulable work-up of patients with venous thromboembolism is important, because the causes can influence the duration and management of anticoagulation therapy, as well as affect other decisions regarding life and health issues.

Antiphospholipid syndrome: pathogenic mechanisms

Despite the strong association between antiphospholipid antibodies (aPL) and thrombosis, the pathogenic role of aPL in the development of thrombosis has not been fully elucidated. Proposed pathophysiological mechanisms may be categorized into two types. First, aPL may act in vivo by disrupting the kinetics of the normal procoagulant and anticoagulant reactions occurring on cell membranes. Second, aPL may stimulate certain cells thereby altering the expression and secretion of various molecules. In this article, we review the mechanisms by which aPL may develop thrombotic events.

Adrenal involvement in the antiphospholipid syndrome: clinical and immunologic characteristics of 86 patients

To describe the clinical and immunologic characteristics of patients with adrenal involvement and antiphospholipid syndrome (APS), we conducted a computer-assisted (PubMed) search of the literature to identify all cases of primary adrenal insufficiency associated with antiphospholipid antibodies published in English, French, and Spanish from 1983 (when APS was first defined) through March 2002. We reviewed 86 patients (80 from the literature plus 6 from our cohort); 55% were male, and the mean age at presentation was 43 +/- 16 years. Sixty-one (71%) patients had primary APS, and 14 (16%) had systemic lupus erythematosus. In 31 (36%) patients, adrenal insufficiency was the first clinical manifestation of APS. Abdominal pain was present in 55% of patients, followed by hypotension (54%), fever (40%), nausea or vomiting (31%), weakness or fatigue (31%), and lethargy or altered mental status (19%). The main finding in imaging techniques was compatible with adrenal hemorrhage (59%) and in histopathologic study was a hemorrhagic infarction with vessel thrombosis (55%). Lupus anticoagulant was detected in 97% of patients and the anticardiolipin antibodies titer was positive in 93% of patients. Most patients (95%) were positive for the IgG isotype of anticardiolipin antibodies, whereas 40% were positive for the IgM isotype. Baseline cortisol levels were decreased in 98% of patients, ACTH hormone levels were increased in 96% of patients, and the cosyntropin stimulation test was positive in 100% of patients tested. Steroid replacement therapy was the most frequent treatment (84%), followed by anticoagulation (52%) and aspirin (6%). Thirty-two of 35 (91%) patients with prolonged anticoagulant therapy were in good health with a mean follow-up of 25 months, whereas 25 of the 69 (36%) patients with outcome data available had died. The results of the present review stress the clinical importance of systematic screening for lupus anticoagulant and anticardiolipin antibodies in all cases of adrenal hemorrhage or infarction. An initial screening for hypoadrenalism is mandatory in any antiphospholipid antibody-positive patient who complains of abdominal pain and undue weakness or asthenia.

Factor VII/VIIa: a new antigen in the anti-phospholipid antibody syndrome

We investigated antibodies to factor VII/VIIa (FVII/VIIa) and five other common target antigens in 33 patients with a history of anti-phospholipid syndrome (APS) and 50 healthy controls using an enzyme-linked immunosorbent assay (ELISA) technique. We found that antibody to FVII/VIIa, a previously unrecognized and common antigen in APS, was present in 67% of patients. Frequencies of antibodies to other target antigens were: anti-beta-2 glycoprotein 1 (anti-beta 2GP1), 88%; anti-cardiolipin (anti-CL), 76%; anti-phosphatidylethanolamine (anti-PE), 67%; anti-phosphatidylserine (anti-PS), 64%; and anti-phosphatidylcholine (anti-PC), 59%. Most patients had antibodies against multiple antigens, but a few were positive for only anti-beta 2GP1 (12%) or anti-CL (3%). Positivity for anti-FVII/VIIa was significantly associated with positivity for anti-PE, anti-PS and/or anti-PC (P < 0.05) but not anti-beta 2GP1. When frequencies of immunoglobulin G (IgG) versus immunoglobulin M (IgM) antibodies were compared, anti-beta 2GP1 IgG correlated with the lupus anticoagulant (P < 0.05) and was significantly more prevalent than IgM, but the reverse was seen for all other antigens. In arterial thrombosis, IgM was more prevalent for all antigens, and was significantly associated with FVII/VIIa, PE and PS, whereas in venous thrombosis, IgG was frequently prevalent, especially in association with FVII/VIIa, beta 2GP1 and CL. In summary, FVII/VIIa is a new and common antigen in APS. Anti-FVII/VIIa is often associated with anti-PE, anti-PS and anti-PC. The IgM class is more frequently associated with arterial thrombosis and the IgG class with venous thrombosis.

Association of the PRO12ALA polymorphism of the PPAR-gamma2 gene with oxidized low-density lipoprotein and cardiolipin autoantibodies in nondiabetic and type 2 diabetic subjects

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a key component in adipocyte differentiation and fat-specific gene expression and may modulate macrophage functions, like proinflammatory activities, and stimulate oxidized low-density lipoprotein (ox-LDL) uptake. We hypothesized that the Pro12Ala polymorphism of the PPAR-gamma2 gene may affect the immune response to ox-LDL. Therefore, we investigated the association of the Pro12Ala polymorphism of the PPAR-gamma2 gene with ox-LDL autoantibodies, as well anticardiolipin antibodies, in a 10-year prospective study. The Pro12Ala polymorphism was genotyped in 119 nondiabetic subjects (age, 45 to 64 years; body mass index [BMI], 19 to 46 kg/m(2)) and 70 type 2 diabetic patients (age, 45 to 65 years; BMI, 19 to 46 kg/m(2)) by the polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) method. Ox-LDL autoantibodies and anticardiolipin antibodies were determined at baseline and after 10 years of follow-up. At baseline, the Pro12Ala polymorphism was not associated with ox-LDL autoantibodies in nondiabetic subjects, whereas type 2 diabetic patients having the Pro12Ala or the Ala12Ala genotypes tended to have higher levels of ox-LDL autoantibodies than did type 2 diabetic patients with the Pro12Pro genotype. At the 10-year follow-up, diabetic subjects having the Ala12 allele had higher ox-LDL autoantibody levels than did diabetic subjects with the Pro12Pro genotype (P =.043 after adjustment for age, gender, BMI, and hemoglobin A(1c) [HbA(1c)] at 5 years). In nondiabetic subjects and regarding anticardiolipin antibodies, no such relationship was observed. We conclude that the Pro12Ala polymorphism of the PPAR-gamma2 gene was associated with increased ox-LDL autoantibodies in type 2 diabetic subjects. Genotype may therefore modulate the oxidative modification of LDL in hyperglycemic milieu.

Antiphosphatidylinositol antibody in deep venous thrombosis patients

Antiphospholipid antibodies are a heterogeneous group of immunoglobulins with specificity for a number of phospholipids, phospholipid-binding proteins and phospholipid-protein complexes. The association between antiphospholipid antibodies and a variety of pathologic disorders, such as arterial and venous thrombosis and recurrent pregnancy loss is recognized as Antiphospholipid Syndrome. The immunoassay currently used to detect antiphospholipid antibodies is the anticardiolipin test. Anticardiolipin antibodies are believed to be polyspecific antibodies that cross-react with all the anionic phospholipids. Therefore, testing only for anticardiolipin antibodies does not always permit detection of all antiphospholipid antibodies, specially when only IgG are evaluated. In a selected population of 74 idiopathic and secondary deep venous thrombosis patients, IgG anticardiolipin, antiphosphatidylinositol and antiphosphatidylserine antibodies were detected by solid-phase immunoassays. Our results show that by testing for each antiphospholipid family, many patients, not evidenced by the standard anticardiolipin assay, were found to be antiphospholipid-positive. The anticardiolipin positive patients have always low, moderate or high levels of antiphospholipid antibodies, suggesting that the antiphospholipid positivity is predictive of anticardiolipin positivity. It should be noted that the patients with only antiphosphatidylinositol positive antibody have a story of nervous system pathology. The meaning of these results is at present under discussion.

Effects of beta2-glycoprotein I and monoclonal anticardiolipin antibodies in platelet interaction with subendothelium under flow conditions

OBJECTIVE

To evaluate whether the effect of human monoclonal anticardiolipin antibodies (aCL) on platelet interaction with the subendothelium under flow conditions is dependent on beta(2)-glycoprotein I (beta(2)GPI).

METHODS

Three monoclonal IgM aCL with anti-beta(2)GPI activity (TM1B3, GR1D5, and EY2C9) obtained from patients with antiphospholipid syndrome, a monoclonal aCL with lupus anticoagulant activity but without anti-beta(2)GPI activity (FRO) obtained from a patient with a splenic lymphoma, and a control monoclonal IgM without aCL activity were used. TM1B3, GR1D5, EY2C9, FRO, and control IgM (30 microg/ml) were added to reconstituted blood containing gel-filtered platelets (200 x 10(9)/liter), factor VIII (100 units/dl), and fibrinogen (1.5 gm/liter). Samples were perfused (wall-shear rate 800 seconds(-1)), with and without the addition of purified beta(2)GPI (20 microg/ml), through annular chambers containing collagen-rich denuded vascular segments, and the percentages of surface covered by platelets and by thrombi were evaluated.

RESULTS

No differences in the percentages of surface covered by platelets and by thrombi were observed among samples with TM1B3, GR1D5, EY2C9, FRO, and control IgM added when reconstituted blood samples without beta(2)GPI were used. However, a significant increase in the percentage of surface covered by platelets was observed in the presence of TM1B3, GR1D5, and EY2C9 but not in the presence of FRO when samples containing beta(2)GPI were used. Increased thrombi formation was induced by TM1B3 and GR1D5 but not by EY2C9 or FRO in samples with added beta(2)GPI.

CONCLUSION

Monoclonal aCL require anti-beta(2)GPI activity to promote platelet interaction with the subendothelium under flow conditions.

Anticardiolipin antibodies as a risk factor for venous thromboembolism in a population-based prospective study

Anticardiolipin antibodies, one of the family of 'antiphospholipid' antibodies, increase the risk of venous thromboembolism in the presence of autoimmune disease. Our objective was to determine prospectively whether there is a positive association between anticardiolipin antibodies and venous thromboembolism in ostensibly healthy adults. We conducted a nested case-control study (n = 317 patients and n = 655 control subjects) in a longitudinal study of over 20 000 participants. Baseline (prediagnosis) anticardiolipin IgG and IgM antibodies were assessed by enzyme-linked immunoassays. Venous thromboembolism was validated using standardized criteria for venous thrombosis and pulmonary embolism. There was no association between anticardiolipin antibodies and subsequent venous thromboembolism occurrence, overall or in any subgroup. For example, the multivariate-adjusted relative risk was 0.88 (95% confidence interval, 0.43, 1.78) for greater than versus less than the 95th percentile of anticardiolipin IgG. In conclusion, in this general population sample, an elevated anticardiolipin antibody level was not a risk factor for venous thromboembolism.

[Valvular heart disease in patients with anti-phospholipid syndrome]

INTRODUCTION

Anti-phospholipid antibodies (APA) may involve heart and valvular heart disease seems to be the most common clinical manifestation.

OBJECTIVES

To study the prevalence and characteristics of valvular heart disease in a large patient population with anti-phospholipid syndrome (APS) and also to analyze the clinical and immunological profile of patients with valvular involvement compared with those without involvement. Patients and methods. Retrospective analysis of 113 patients diagnosed of APS. Eighty-one percent were females and the mean age was 39 years (SD:14). Sixty-two percent of patients were diagnosed of primary APS (70 patients) and the remaining 38% (43 patients) corresponded to patients with APS associated with systemic lupus erythematosus (SLE). The median follow-up of patients was 55 months (range: 7-144 months). The cardiologic assessment was performed by means of transthoracic echocardiogram. The study of anti-lupus anticoagulant (AL) was performed by means of coagulometric assays and measurement of anticardiolipin antibodies (aCL), anti-beta2 glycoprotein I (abeta2-PGI) and anti-prothrombin (aPT) by ELISA.

RESULTS

The prevalence of valvular heart disease was 19%. The mitral valve was mostly involved (91%) and the most common structural abnormality corresponded to mitral insufficiency. Valvular replacement was required in 24% of patients. In the subgroup of patients with valvular heart disease, a significantly higher prevalence was observed in the following parameters: total thrombosis (71% versus 49%; p = 0.05), arterial thrombosis (57% versus 23%; p = 0.002), stroke (38% versus 13%; p = 0.01), trombocitopenia (71% versus 45%; p = 0.02), hemolytic anemia (29% versus 9%; p = 0.02), and livedo reticularis (48% versus 3%; p < 0.0001). As for immunological differences, only a higher prevalence of LA was found (81% versus 59%; p= 0.04) and abeta2-GPI (IgG isotype) (43% versus 22%; p = 0.05) in patients with valvular heart disease.

CONCLUSIONS

Valvular heart disease is more frequent in pa-tients with APS and mitral insufficiency is the most common lesion. In a patient with the diagnosis of APS, an echocar-digram should be obtained in his/her initial assessment and regular controls should be obtained in the follow-up.

[Relative value of different antiphospholipid antibodies detected in a department of internal medicine: retrospective study of 124 patients]

PURPOSE

The value of antiphospholipid antibodies (aPL) detected in the sera of the patients of an Internal Medicine department is not univocal and is still much debated. To test the contribution of such new markers, we reviewed the records of patients having antiphospholipid antibodies detected between 1996 and 1997.

METHODS

One hundred and twenty four patients, having at least one of these two aPL: lupus anticoagulant (LA), anticardiolipin antibodies (aCL), or one of these two anti-proteins: anti-beta 2glycoprotéin I antibodies (anti-beta 2GPI) or anti-prothrombin antibodies (aPT), were studied. LA was detected by a PTT-LA technique and aCL, anti-beta 2GPI and aPT by ELISA-sandwich techniques. For each patient we recorded sex, age, personal and familial history of thrombosis, fetal losses and systemic disease, the reason of aPL detection, the final diagnosis, activated partial thromboplastin time (aPTT), platelets count and type of aPL.

RESULTS

The population was composed of 77 women (62%) and 47 men (38%) with a mean age of 54 years [12-92 years]. A thrombocytopenia was strongly correlated to aCL presence (OR = 6.15 et p = 0.03). The reason of aPL detection was venous thrombosis, recurrent fetal losses, systemic disease, infectious disease or fortuitous discovery of a prolonged aPTT. The final diagnosis was a systemic disease in 57% of cases, an infectious disease in 14.5%, a thrombosis in 4.5% and a neoplasia in 3%. LA was detected in 54% of patients, aCL in 39.5%, anti-beta 2GPI in 23% and aPT in 31%. No relationship between the aPTT value and the type of aPL could be established.

CONCLUSION

Our study shows that familial histories of venous thrombosis or systemic disease are useful to enhance antiphospholipid antibodies detection; that LA is mostly associated to systemic and infectious diseases; that aCL and anti-beta 2GPI are predominant in case of venous thrombosis and that thrombocytopenia has to enhance aCL detection and the discussion about a possible APS.

Anti-beta2-glycoprotein I antibodies in pediatric systemic lupus erythematosus and antiphospholipid syndrome

OBJECTIVE

To determine whether serum beta2-glycoprotein I antibody (anti-beta2GPI) detection improves identification of pediatric subjects at risk for antiphospholipid syndrome (APS).

METHODS

Serum antiphospholipid antibodies (aPL) were identified by anticardiolipin enzyme-linked immunosorbent assay (ELISA), lupus anticoagulant assays, and syphilis screening in children with primary APS, systemic lupus erythematosus (SLE), or SLE plus APS. Anti-beta2GPI level and isotype were determined by beta2GPI ELISA and correlated with clinical manifestations and other aPL assays.

RESULTS

One hundred-ten subjects under 22 years of age and of mixed ethnicity were evaluated. Fifty-seven had SLE (including 14 with APS), 25 had primary APS, 16 had SLE-like APS, 6 were healthy children with aPL detected incidentally, 4 had other rheumatic diseases and 2 had other conditions. Anti-beta2GPI were detected in 48% of SLE subjects and did not improve aPL detection over standard tests. Anti-beta2GPI were associated with stroke (P = 0.014), but not with other APS manifestations, and were rarely detected in primary APS. Among subjects with APS manifesting as chronic thrombocytopenia, anti-beta(2)GPI distinguished subjects with SLE from those with primary APS.

CONCLUSIONS

With the exception of stroke, anti-beta2GPI detection does not improve identification of pediatric APS over that of traditional aPL assays. Anti-beta2GPI are rare in pediatric primary APS, but may predict evolution of chronic thrombocytopenia to SLE.

Antiphospholipid antibodies after surgical exposure to topical bovine thrombin

Exposure to topical bovine thrombin during surgery frequently results in the development of antibodies to multiple protein and carbohydrate antigens. We investigated the frequency of increased levels of antibodies to cardiolipin and beta(2)-glycoprotein I (beta(2)-GPI) in two groups of patients, one exposed to bovine thrombin during cardiovascular surgery (n = 151) and a "control" group undergoing cardiovascular surgery but without exposure to bovine thrombin (n = 11). Anticardiolipin antibody levels were increased before surgery in 10 of the 151 patients exposed to topical thrombin (6.6%). Four to 8 weeks after surgery, 84 patients (55.6%) had increased anticardiolipin antibody levels (P <.0001). In the control group, an increased anticardiolipin antibody level was present in a single patient before and after surgery (9%). Increased levels of antibodies to bovine and human beta(2)-GPI were also observed after surgery in the patients exposed to topical thrombin (37.7% and 38.2%, respectively). Increased anticardiolipin levels correlated with higher levels of antibody to bovine, but not human, beta(2)-GPI. In addition, increased levels of anticardiolipin antibody were associated with higher levels of antibodies to bovine factor V and prothrombin, as well as human factor V. Antibody binding on an enzyme-linked immunosorbent assay conducted to detect anticardiolipin antibody was dependent on the presence of anionic phospholipid, indicating that binding was not linked to the fetal bovine serum in the blocking buffer alone. Seven of 8 patients with delayed thromboembolic complications had increased anticardiolipin IgG antibody levels after surgery, but this association was not statistically significant. Nevertheless, our findings support the recommendation that the clinical safety of these commonly used hemostatic agents should be reassessed.

Low levels of activated protein C in patients with systemic lupus erythematosus do not relate to lupus anticoagulants but to low levels of factor II

The presence of lupus anticoagulants (LAC) in plasma is a major risk factor for thrombosis. An attractive hypothesis to explain a LAC-mediated thrombotic tendency is that LAC interfere with activation of protein C, a natural antithrombotic in plasma. We investigated the relationship between LAC and protein C activation in vivo. We selected 20 patients with systemic lupus erythematosus (SLE) with LAC (and not using oral anticoagulants), 36 patients with SLE without LAC and 25 healthy volunteers. In these, we measured circulating levels of activated protein C (APC), prothrombin (FII), free protein S, C4BP, protein C, and antibodies to protein C, protein S, FII and beta2-glycoprotein I (beta2GPI). In SLE patients (n = 56), mean levels of APC, FII and free protein S were significantly (P < 0.001) lower than those in healthy volunteers (respectively 13%, 17% and 14%). Mean protein C levels and C4BP levels were similar for SLE patients and healthy volunteers. In contrast to the above hypothesis, the decreased levels of APC could not be attributed to the presence of LAC. Levels of APC were correlated with both FII levels and protein C levels. Decreased levels of APC, FII, protein C and free protein S were related to the presence of anti-FII antibodies. None of the patients had antibodies against protein C or protein S. In conclusion, although the mean levels of APC, FII and free protein S were significantly decreased in SLE patients, no correlation with LAC was found. However, anti-FII antibodies were related to decreased levels of APC, FII, protein C, free protein S and C4BP. As FII levels, and not protein C levels, were decreased in SLE patients and correlated with APC levels, we conclude that the decreased FII levels are responsible for the low levels of APC.

Antiphospholipid antibodies induce monocyte chemoattractant protein-1 in endothelial cells

The presence of antiphospholipid Ab is associated with increased risk of thrombosis. The monocyte-endothelial cell interaction has been suggested to play a key role at the site of vascular injury during thrombosis. Therefore, we tested the effect of anticardiolipin Abs (aCL) on the production of monocyte chemoattractant protein-1 (MCP-1) in HUVEC. We found that monoclonal aCL as well as IgG fractions from patients with antiphospholipid syndrome (APS-IgG) could induce the production of MCP-1 in HUVEC. The ability of IgG aCL to induce MCP-1 production could be abrogated by preabsorption with cardiolipin liposomes. Simultaneous addition of either monoclonal aCL or APS-IgG with IL-1beta resulted in synergistic increase in MCP-1 production, whereas the addition of control IgG lacking aCL activity did not alter IL-1beta-induced levels of MCP-1. MCP-1 mRNA expression was also up-regulated when HUVEC were incubated with either APS-IgG or monoclonal aCL, and down-regulated by the treatment of dexamethasone. In addition, we found that serum levels of MCP-1 in 76 systemic lupus erythematosus patients correlated well with the titers of IgG aCL. Collectively, these results indicate that aCL could promote endothelial cell-monocyte cross-talk by enhancing the endothelial production of MCP-1, thereby shifting the hemostatic balance toward the prothrombotic state of APS.

Clinical relevance of antiprothrombin antibodies

Antiprotrombin antibodies belong to the family of antiphospholipid antibodies (aPLs). The clinical relevance of antiprothrombin antibodies has not been established and it depends on the applied detection method. Antibodies against phosphatidylserine-prothrombin complex (aPS/PT) are closely associated with clinical features of antiphospholipid syndrome (APS) and lupus anticoagulant rather than antibodies against prothrombin alone. The determination of aPS/PT in routine clinical practice should be done in conjunction with other aPLs detection to improve the likelihood of recognising the APS, which would ultimately facilitate the management of the disease.

Abnormal optical waveform profiles in coagulation assays from patients with antiphospholipid antibodies

Transmittance waveforms are the optical data generated during clot formation on photo-optical coagulation analyzers and are used to define specific events of the clotting reactions. Thus, a prothrombin time (PT) or an activated partial thromboplastin time (aPTT) can be divided into a pre-coagulation phase, a coagulation phase, and a post-coagulation phase. These phases are further characterized by parameters that define the timing, the rate, the 'slope', and the magnitude of the signal change of the reactions. We investigated the transmittance waveform parameters obtained during PT and aPTT of patients with antiphospholipid antibodies (APLA) who were or were not taking warfarin, normal donors, and non-APLA patients taking warfarin. An abnormal deflection in the pre-coagulation phase of the PT (called slope 1) was observed in 61.5% of the patients with APLA, in contrast to 5.9% of non-APLA patients taking warfarin (P= 0.0015). The presence of an abnormal PT slope 1 was reagent specific and was inversely correlated with the anticardiolipin antibody immunoglobulin G (IgG) level, which suggests that the abnormal PT slope 1 may reflect interactions between patient IgG and components from the thromboplastin, possibly phospholipids. The abnormal PT slope 1 values may be of diagnostic utility in the identification of patients with antiphospholipid syndromes.

Identification of anti-thrombin antibodies in the antiphospholipid syndrome that interfere with the inactivation of thrombin by antithrombin

The combined presence of anti-phospholipid (PL) Ab, including lupus anticoagulants (LAC) and/or anticardiolipin Ab (aCL), and thrombosis is recognized as the antiphospholipid syndrome (APS). LAC are detected as an inhibitory effect on PL-restricted in vitro blood coagulation tests, and are comprised mainly of Ab against beta(2) glycoprotein I and prothrombin (PT). Recently, anti-PT Ab (aPT) were found to be associated with thrombosis by some investigators, although this is not confirmed by others. Considering that aPT are heterogeneous in patients and that PT is converted into thrombin, we hypothesize that certain aPT in patients may bind to thrombin, and that some of such anti-thrombin Ab may interfere with thrombin-antithrombin (AT) interaction and thus reduce the AT inactivation of thrombin. To test this hypothesis, we searched for anti-thrombin Ab in APS patients and then studied those found for their effects on the AT inactivation of thrombin. The results revealed that most, but not all, aPT-positive patient plasma samples contained anti-thrombin Ab. To study the functional significance of these Ab, we identified six patient-derived mAb that bound to both PT and thrombin. Of these mAb, three could reduce the AT inactivation of thrombin, whereas others had minimal effect. These findings indicate that some aPT in patients react with thrombin, and that some of such anti-thrombin Ab could inhibit feedback regulation of thrombin. Because the latter anti-thrombin Ab are likely to promote clotting, it will be important to develop specific assays for such Ab and study their roles in thrombosis in APS patients.

Statins prevent endothelial cell activation induced by antiphospholipid (anti-beta2-glycoprotein I) antibodies: effect on the proadhesive and proinflammatory phenotype

OBJECTIVE

To investigate the ability of statins, the inhibitors of the hydroxymethylglutaryl-coenzyme A reductase enzyme, to affect endothelial cell activation induced by anti-beta2-glycoprotein I (anti-beta2GPI) antibodies in vitro.

METHODS

Human umbilical vein endothelial cell (HUVEC) activation was evaluated as U937 monocyte adhesion, E-selectin, and intercellular adhesion molecule I (ICAM-1) expression by cell enzyme-linked immunosorbent assay and as interleukin-6 (IL-6) messenger RNA (mRNA) expression by RNA protection assay. E-selectin-specific nuclear factor kappaB (NF-kappaB) DNA-binding activity was evaluated by the gel-shift assay. HUVECs were activated by polyclonal affinity-purified IgG, human monoclonal IgM anti-beta2GPI antibodies, human recombinant IL-1beta, tumor necrosis factor alpha, or lipopolysaccharide (LPS).

RESULTS

Fluvastatin reduced, in a concentration-dependent manner (1-10 microM), the adhesion of U937 to HUVECs and the expression of E-selectin and ICAM-1 induced by anti-beta2GPI antibodies as well as by cytokines or LPS. Another lipophilic statin, simvastatin, displayed similar effects but to a lesser extent than fluvastatin. The inhibition of E-selectin expression exerted by fluvastatin was related to the impairment of NF-kappaB binding to DNA. Moreover, the drug attenuated the expression of IL-6 mRNA in HUVEC exposed to anti-beta2GPI antibodies or cytokines. Incubation of HUVECs with mevalonate (100 microM), concomitantly with fluvastatin, greatly prevented the inhibitory effect of statin.

CONCLUSION

Endothelial activation mediated by anti-beta2GPI antibody can be inhibited by statins. Because of the suggested role of endothelial cell activation in the pathogenesis of antiphospholipid syndrome (APS), our data provide, for the first time, a rationale for using statins as an additional therapeutic tool in APS.

The effects of a human IgM monoclonal anticardiolipin antibody on pregnancy in a transgenic mouse model

The clinical features of antiphospholipid (or Hughes') syndrome (APS) are most commonly seen in individuals who have raised levels of IgG anticardiolipin antibodies. Most murine models of the syndrome have involved the administration of such antibodies to normal mice. However, APS can occur in the presence of raised levels of serum IgM anticardiolipin antibodies alone. The present study was designed to see if an IgM monoclonal antibody can induce changes in mice similar to those seen in human APS. This antibody, BH1, has previously been derived from a patient with primary APS. In its ligand-binding and idiotypic characteristics it is representative of antiphospholipid antibodies (aPL) found in the serum of patients with APS. In order to minimise the immune response to human IgM, we used transgenic mice (F15) which express, and are predicted to be tolerant of, human immunoglobulin mu chains. The features of APS may develop more readily in individuals who have an existing autoimmune disorder, such as systemic lupus erythematosus (SLE). We therefore crossed these transgenic mice with New Zealand Black (NZB, SLE-prone) mice, and used the progeny (F15 x NZB/F1) in our experiments. Twenty-four F15 x NZB/F1 mice were given BH1, or a control IgM antibody, (A5566) immediately preceding and then three times during pregnancy. There was a reduction in the mean number of foetuses in animals given BH1 compared with those given A5566 (8.6 vs 11.0; P < 0.05), and a similar reduction in mean total foetal weight per pregnancy (9.05 vs 12.73 g; P < 0.05). Two mice showed a marked reduction in platelet count. No evidence of thrombosis was detected macroscopically or histologically. Our results show a lower incidence of APS-type features compared to previous studies in which mice have been administered aPL. This may be because BH1 is an IgM antibody. Nevertheless, the data support the concept that IgM aPL of particular ligand-binding specificities may have a direct pathogenetic role in certain cases of human APS.

Oxidized low-density lipoprotein and autoimmune antibodies in patients with antiphospholipid syndrome with a history of thrombosis

The prevalence and clinical significance of plasma oxidized low-density lipoprotein (oxLDL) and antibodies against oxLDL (anti-oxLDL) were evaluated in patients with antiphospholipid syndrome (APS). OxLDL and IgG anti-oxLDL were determined by enzyme-linked immunosorbent assay in plasma samples from 80 patients with APS. Positive values (mean + 3 SD) for oxLDL and anti-oxLDL were found in 21 (26%) and 19 (24%) of 80 patients with APS, respectively These values were significantly higher than those in healthy subjects. Levels of oxLDL and anti-oxLDL antibodies in subgroupings of patients with APS who had experienced thrombotic events were compared. There were significant differences among the groups for the levels of both oxLDL and anti-oxLDL antibodies. Pairwise comparisons between the groups yielded similar but not identical results. There was a significant, positive correlation between levels of plasma oxLDL and anti-oxLDL. These results suggest that elevated levels of plasma oxLDL and anti-oxLDL may be risk factors and potential markers for thrombosis, especially for arterial thrombotic events, in patients with APS.

Optimising testing for phospholipid antibodies

AIM

To compare anticardiolipin (ACL) and anti-beta2 glycoprotein 1 (beta2gp1) enzyme linked immunosorbent assays (ELISAs) in the diagnosis of antiphospholipid syndrome (APS) and to incorporate these results into a meta-analysis of published data.

METHOD

Three representative commercial ACL ELISAs and an in house beta2gp1 assay were optimised and then assessed on 124 sera from normal donors, patients with infection, or patients with APS. A Medline search was screened for papers meeting defined criteria to conduct a meta-analysis. The performance of the assays used in this study was included.

RESULTS

A non-quantitative ACL assay performed at least as well as the anti-beta2gp1 assay in the diagnosis of APS. Meta-analysis confirmed that neither assay is perfect, although the anti-beta2gp1 assay had a higher specificity and lower sensitivity than the ACL assay.

CONCLUSIONS

The pooled data suggest that the ACL assay is used to investigate thrombosis without overt underlying pathology and that the improved specificity of the anti-beta2gp1 assay is exploited where infection, connective tissue disease, or atheroma are present.

IgG subclass distribution of antibodies against beta(2)-GP1 and cardiolipin in patients with systemic lupus erythematosus and primary antiphospholipid syndrome, and their clinical associations

OBJECTIVES

To determine the immunoglobulin G (IgG) subclass distribution of anticardiolipin (aCL) and anti-beta(2)-glycoprotein 1 (beta(2)-GP1) antibodies (abeta(2)-GP1), and to examine possible associations between the different abeta(2)-GP1 and aCL subclasses and the main clinical manifestations of the antiphospholipid syndrome (APS).

METHODS

We studied 130 patients with systemic lupus erythematosus and 35 patients with primary APS. We used enzyme-linked immunosorbent assays to measure IgG aCL and abeta(2)-GP1 and to determine the IgG subclass distribution of these two autoantibodies.

RESULTS

When the number of patients positive for each subclass was examined, IgG(3) and IgG(2) aCL were more frequent (63.5 and 54.1% of patients were positive for the two subclasses, respectively), while for abeta(2)-GP1 IgG(2) was the most prevalent subclass (81.8% of patients were positive). IgG(2) aCL was significantly associated with arterial thrombosis (P=0.023) and fetal loss (P=0.013), and IgG(3) aCL was significantly associated with arterial thrombosis (P=0.0003) and fetal loss (P=0.045). IgG(2) abeta(2)-GP1 was associated with venous thrombosis (P=0.012) and IgG(3) abeta(2)-GP1 was associated with venous thrombosis (P=0.036) and fetal loss (P=0.024).

CONCLUSIONS

The IgG(2) predominance of abeta(2)-GP1 suggests that the antibody response against beta(2)-GP1 may be T-cell-independent. As IgG(2) and IgG(3) differ in their effector functions, their association with the same clinical manifestations (i.e. thrombosis and fetal loss) suggests that more than one mechanism may be involved in the pathogenesis of thrombosis and fetal loss in APS.

Accelerated atheroma, antiphospholipid antibodies, and the antiphospholipid syndrome

Indirect data coming from animal studies and in vitro observations support the contention that the mere presence of antiphospholipid antibodies may be sufficient to increase atheroma development, regardless of other predisposing factors. It seems that humoral and cellular immune responses to beta 2-glycoprotein I can play an important role in mediating the increased propensity to atherosclerosis.