The "primary" antiphospholipid syndrome: major clinical and serological features

The antiphospholipid syndrome--the association of venous and/or arterial thromboses, often accompanied by thrombocytopenia in the presence of the antiphospholipid antibodies ("lupus anticoagulant" antibodies to cardiolipin)--is seen mainly in patients with systemic lupus erythematosus (SLE) and the closely related "lupus-like" disease, i.e., lupus patients not conforming to the 1982 revised American Rheumatism Association classification for SLE. It is also seen in a group of patients who do not manifest any of the major clinical or serologic features of SLE, the majority of whom do not appear to progress to classical lupus. A multicenter study of 70 of these patients is documented and their major clinical and serologic characteristics examined: They have been characterized as suffering from a "primary" antiphospholipid syndrome and present typically with a history of deep vein thromboses, often accompanied by pulmonary thromboembolism, which in a few is complicated by thromboembolic pulmonary hypertension, arterial occlusions (most commonly strokes), or fetal loss. The events are often recurrent and may be accompanied by hemocytopenias (thrombocytopenia and less frequently Coombs positivity and/or hemolytic anemia). They are often antinuclear antibody-negative and are always negative for antibodies to dsDNA and to ENA, typical serologic features of SLE. There may be a family history of SLE or a familial clotting tendency in a minority. The group of patients presented appears to be closely related, but distinctly separate from SLE.     

Recent insights into antiphospholipid antibody-mediated thrombosis.

The clinically relevant antiphospholipid antibodies (APA) include anticardiolipin antibodies and lupus anticoagulant. Most autoimmune APA require the presence of a cofactor for phospholipid binding, and the growing list of candidate cofactors has prompted redefinition of APA to 'antiphospholipid protein antibodies'. Current evidence favours beta2-glycoprotein I (beta2GPI) and prothrombin as the primary antigens for anticardiolipin antibodies and lupus anticoagulant respectively. Patients with APA show a predisposition for venous and arterial thromboembolism, recurrent fetal loss, thrombocytopenia and a number of neurological syndromes and miscellaneous conditions. The association between APA and thrombosis has been well documented, but a definite mechanism remains to be clarified. Proposed mechanisms have included disruption of endothelial regulatory processes, impairment of fibrinolysis, augmented platelet activation and/or adhesion, inhibition of antithrombin activity and negation of the anticoagulant effects of beta2GPI and annexin V. In this review we describe recent insights into the role of beta2GPI as a natural anticoagulant, the procoagulant effects of APA on the Protein C system, the interactions between APA and prothrombin resulting in augmentation of thrombin generation, and cellular expression of Tissue Factor in patients with APA. Cellular immunity to beta2GPI is also discussed. Elucidation of these pathophysiological mechanisms may shed further light on the association between APA and thrombosis.     

The lupus anticoagulant, pulmonary thromboembolism, and fatal pulmonary hypertension.

A patient with a circulating lupus anticoagulant in the absence of systemic lupus erythematosus developed recurrent deep venous thromboses and pulmonary emboli. Pulmonary emboli recurred despite prolonged oral anticoagulant therapy and resulted in fatal pulmonary arterial hypertension. Extended anticoagulant therapy alone may not prevent recurrent thromboembolism in patients with a lupus anticoagulant. Pulmonary thromboembolism may be an important factor in the pathogenesis of pulmonary hypertension in patients with a lupus anticoagulant.     

Antiphospholipid-thrombosis syndromes

Antiphospholipid antibodies are strongly associated with thrombosis and appear to be the most common of the acquired blood protein defects causing thrombosis. Based upon our experience, approximately 25% of patients with unexplained venous thrombosis, approximately 60% of patients with cerebrovascular thrombosis, approximately 37% of patients with transient ischemic attacks, approximately 18% with premature coronary artery thrombosis and approximately 60% of patients with recurrent fetal loss (recurrent miscarriage syndrome) harbor antiphospholipid antibodies. Although the precise mechanism(s) whereby antiphospholipid antibodies alter hemostasis to induce a hypercoagulable state remain unclear, several theories have been advanced. Since the aPTT is unreliable in patients with lupus anticoagulant and is not usually prolonged in patients with anticardiolipin antibodies, definitive tests, ELISA for IgG, IgA and IgM anticardiolipin antibodies and the dilute Russel's viper venom time (followed by cephalin correction for confirmation) for lupus anticoagulant should be immediately ordered when suspecting the antiphospholipid syndrome in individuals with otherwise unexplained thrombotic or thromboembolic events or recurrent fetal loss. However, if one strongly suspects antiphospholipid thrombosis syndrome clinically and assays for lupus anticoagulants and anticardiolipin antibodies are negative, specific assays for all three idiotypes of phosphatidylserine, phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol and phosphatidylglycerol are available and should be considered. These may clearly be indicated for difficult diagnostic cases of fetal wastage syndrome, and cerebrovascular events, but their significance in other types of thrombosis, particularly venous, remains unclear at present. Since about 65% of patients with antiphospholipid antibodies will fail warfarin therapy (rethrombose), it is important to define this common defect and institute appropriate antithrombotic therapy for appropriate time periods.     

Lupus anticoagulants in children

Lupus anticoagulant and ACAs are made up of heterogeneous IgG and IgM antibodies that prolong in vitro clotting times and are associated with increased risks of venous and arterial thrombosis, recurrent fetal loss, and autoimmune thrombocytopenia and anemia. These clinical findings with the appropriate laboratory results make up the antiphospholipid antibody syndrome. The antiphospholipid antibodies found in this syndrome are directed against a variety of phospholipid binding proteins of which beta2-glycoprotein and prothrombin are considered to be common antigens. Children who present with thrombosis and are positive for lupus anticoagulant and ACAs have similar clinical presentations and prognoses as adults. Isolated lupus anticoagulant and ACAs in children who are asymptomatic likely do not lead to clinical complications and are transient.     

Antiphospholipid antibodies: anticardiolipin and the lupus anticoagulant in systemic lupus erythematosus (SLE) and in non-SLE disorders. Prevalence and clinical significance

PURPOSE: To determine the prevalence of lupus anticoagulant and anticardiolipin in systemic lupus erythematosus (SLE) and in non-SLE disorders, and to evaluate the clinical significance of these autoantibodies as they relate to thromboembolic events, neuropsychiatric disorders, thrombocytopenia, and fetal loss. DATA IDENTIFICATION: A computer-assisted search of the literature (MEDLINE, 1966 to 1989) and review of the bibliographies of all identified articles. STUDY SELECTION: Series of ten or more subjects were included if the assays used for detecting lupus anticoagulant or anticardiolipin met the specified minimal criteria for validity. DATA EXTRACTION: Series were categorized according to antibody type and underlying disease. A systematic appraisal of patient selection methods, study design, and assay methods was done. RESULTS OF DATA ANALYSIS: An analysis of 29 published series (comprising over 1000 patients with SLE) yielded an average frequency of 34% for the lupus anticoagulant and 44% for anticardiolipin. Antiphospholipid antibodies are also prevalent in patients with various non-SLE disorders. In patients with SLE, a statistically significant association exists between the presence of either antibody and a history of thrombosis, neurologic disorders, or thrombocytopenia. The available data suggest, but do not firmly support, an association between antiphospholipid antibodies and history of fetal loss in women with SLE. Contrary to prevailing opinion, none of these associations have been shown conclusively in patients with non-SLE disorders. CONCLUSIONS: The results of predominantly retrospective series suggest that for certain persons (patients with SLE or closely related disorders) antiphospholipid antibodies may be important risk factors for thrombosis, neurologic disease, thrombocytopenia, and fetal loss. Standardized tests for lupus anticoagulant and anticardiolipin, as well as long-term, prospective clinical studies, are needed to determine the prognostic value of antiphospholipid antibodies.     

Antiphospholipid antibody syndrome: immunologic and clinical aspects

Antiphospholipid antibody is associated with a clinical syndrome of vascular thrombosis, thrombocytopenia, recurrent fetal loss, and livedo reticularis, whether or not a clinical diagnosis of systemic lupus erythematosus (SLE) coexists. A positive antiphospholipid antibody test is defined by enzyme-linked immunosorbent assay (ELISA) (antiphospholipid antibody itself) or by coagulation assay (lupus anticoagulant). These are similar but not identical antibodies. The test for syphilis is less closely related to the preceding two and is less regularly associated with clinical complications. The mechanism of action of either antiphospholipid antibody or lupus anticoagulant is as yet unknown. SLE-induced but not infection-induced antiphospholipid antibody has immunoglobulin G2 (IgG2) and IgG4 predominance. It recognizes all negatively charged phospholipids, but various physical characteristics of the phospholipids alter the recognition patterns. Treatment for the antiphospholipid antibody syndrome has not been clearly defined. Anticoagulation with aspirin, heparin, or warfarin is currently favored. A role for corticosteroid remains to be demonstrated.     

A case of Waldenstroem's disease with a monoclonal IgM antiphospholipid antibody

The antiphospholipid syndrome (APS) was described in 1983 as a clinical entity characterized by venous and arterial thrombosis, thrombocytopenia, and recurrent fetal loss. The serological markers of APS are antiphospholipid antibodies (APLA) directed mainly against anionic phospholipids, usually cardiolipin but also phosphatidylserine. Some APLA exhibit lupus anticoagulant activity. Monoclonal gammopathy sometimes occurs with the presence of autoantibodies. In this paper, we describe a patient with the diagnosis of immunocytoma with an IgM, kappa paraprotein with apparent specificity against anionic phospholipids, and lupus anticoagulant activity, but no clinical signs of APS. We describe in this patient the presence of a high titer of monoclonal APLA, which does apparently not induce the clinical symptoms of APS. This might be indicative for the presence of pathogenic and nonpathogenic antiphospholipid antibodies.     

Antibodies to factor XII and recurrent fetal loss in patients with the anti-phospholipid syndrome

Forty female patients with either primary anti-phospholipid syndrome (n = 26) or systemic lupus erythematosus (anti-phospholipid syndrome positive) (n = 14) were investigated for levels of factor XII, the presence of lupus anticoagulant and antibodies to cardiolipin, beta 2-glycoprotein I and factor XII. Twenty-one patients had a history of recurrent fetal loss (> 2, mean = 2.6). Lupus anticoagulant positivity showed a weak association with recurrent fetal loss (odds ratio = 1.1). While there was no association between the presence of antibodies to cardiolipin or beta 2-glycoprotein I with recurrent fetal loss, antibodies to factor XII showed a strong and statistically significant association (odds ratio = 5.4, P = 0.025).     

Animal models of the antiphospholipid syndrome.

The antiphospholipid antibody syndrome (APS) is characterized by thrombocytopenia, recurrent thromboembolic phenomena and recurrent fetal loss, in association with anticardiolipin antibodies (aCL) and/or lupus anticoagulant (LA). Owing to the ethical and practical restrictions of experimentation on humans, we have to look to animal experimentation to broaden our knowledge of the pathogenesis and management of APS. Work has been carried out predominantly on strains of naive mice in which APS has been induced, passively and actively, using autoantibodies, autoantigens and other antigens. Studies of autoimmune-prone mice and naive rabbits are present in the literature, to a lesser degree. We review the various animal models of the pathogenesis of APS, whether spontaneous or induced, which have been developed over the years. Although several of the models have provided insights into the relationship between antiphospholipid antibodies and fetal loss, very few give guidance to explain the link with thrombosis. Novel or experimental therapeutic regimens have to be tested on appropriate animal models before any kind of human clinical trials may proceed. The regimens devised thus far are also reviewed.     

Induction of anti-phospholipid syndrome in naive mice with mouse lupus monoclonal and human polyclonal anti-cardiolipin antibodies.

The primary anti-phospholipid syndrome is characterized by recurrent venous and arterial thromboembolic phenomena, recurrent fetal loss, thrombocytopenia, and serological evidence of anti-cardiolipin (aCL) antibodies or/and the presence of lupus anticoagulant (prolonged activated partial thromboplastin time). The exact role of aCL antibodies in pathogenesis is not clear and the mechanism by which the antibodies may induce the various manifestations is unknown. In the current study we evaluated the effect of passive transfer of aCL antibodies (to the tail vein of naive mice) on fecundity, fetal loss (fetal resorption), and the weight of embryos and placentae. Two types of aCL antibodies were employed: (i) mouse monoclonal aCL antibodies derived from a BALB/c mouse in which experimental systemic lupus erythematosus was induced by a pathogenic idiotype (idiotype 16/6) of anti-DNA antibodies and (ii) polyclonal IgG and IgM aCL antibodies derived from serum of a patient with primary anti-phospholipid syndrome. After infusion of either antibody (10 micrograms per mouse) we could demonstrate lower fecundity rate, increased resorption index of embryos (equivalent to recurrent fetal loss), lower number of embryos per pregnancy, and lower mean weights of embryos and placentae in comparison to mice infused with appropriate control immunoglobulins. We conclude that the aCL antibodies may have direct effects on fecundity and on the outcome of pregnancy.     

Antiphospholipid antibodies in pediatrics

Antiphospholipid antibody syndrome has been associated with vascular thrombosis, thrombocytopenia, hemolytic anemia, livedo reticularis, neurologic disorders, and recurrent fetal loss. The diagnosis of antiphospholipid syndrome is given in the presence of an elevated anticardiolipin antibody lupus anticoagulant in addition to a thrombotic event. Antiphospholipid antibodies are responsible for a majority of thrombotic events in children. These antibodies can present as a primary syndrome or secondary to other diseases, such as systemic lupus erythematosus. Anticoagulation therapy with heparin and low-dose aspirin is the recommended treatment in pediatric patients.     

Antiphospholipid syndrome: laboratory testing and diagnostic strategies

The antiphospholipid syndrome (APS) is diagnosed in patients with recurrent thromboembolic events and/or pregnancy loss in the presence of persistent laboratory evidence for antiphospholipid antibodies. Diagnostic tests for the detection of antiphospholipid antibodies include laboratory assays that detect anticardiolipin antibodies, lupus anticoagulants, and anti-β(2)-glycoprotein I antibodies. These assays have their origins beginning >60 years ago, with the identification of the biologic false positive test for syphilis, the observation of "circulating anticoagulants" in certain patients with systemic lupus erythematosus, the identification of cardiolipin as a key component in the serologic test for syphilis, and the recognition and characterization of a "cofactor" for antibody binding to phospholipids. Although these assays have been used clinically for many years, there are still problems with the accurate diagnosis of patients with this syndrome. For example, lupus anticoagulant testing can be difficult to interpret in patients receiving anticoagulant therapy, but most patients with a thromboembolic event will already be anticoagulated before the decision to perform the tests has been made. In addition to understanding limitations of the assays, clinicians also need to be aware of which patients should be tested and not obtain testing on patients unlikely to have APS. New tests and diagnostic strategies are in various stages of development and should help improve our ability to accurately diagnose this important clinical disorder.     

Multiple transient ischaemic attacks and a mild thrombotic stroke in a HIV-positive patient with anticardiolipin antibodies

Antiphospholipid antibodies (APA) have been reported to be associated with thrombosis in systemic lupus erythematosus (SLE) and in many other clinical groups. However, although these antibodies have been identified in a substantial number of patients infected with the human immunodeficiency virus (HIV), in this case an association with thrombosis has not been evident. We describe a patient with HIV infection who had anticardiolipin antibodies (ACA) but no lupus anticoagulant (LA) who had recurrent transient ischaemic attacks (TIAs) and a mild stroke.     

Antiphosphatidylethanolamine antibody as the sole antiphospholipid antibody in systemic lupus erythematosus with thrombosis.

A previously healthy 34-year-old woman, was diagnosed as having systemic lupus erythematosus (SLE), with membranous glomerulopathy which improved rapidly. Neither lupus anticoagulant nor anticardiolipin antibodies were detected in her plasma. After three months of total remission, she developed a severe pulmonary thromboembolism for which no specific biological cause was found. Her plasma was analysed for different antiphospholipid antibodies: lupus anticoagulant and anticardiolipin antibodies were again negative. Using an ELISA prepared with either five different anionic phospholipids or zwitterionic phosphatidylethanolamine, solely an anti-phosphatidylethanolamine IgG was discovered in her plasma. In lupus patients, the presence of antiphospholipid antibodies is now well recognized as a high risk factor for repeated thrombosis and/or recurrent abortions. This case suggests that the presence of antiphosphatidylethanolamine antibody should be investigated in cases of unexplained thrombosis in SLE, where the usual clinical and biological investigations have failed to shed light.     

Antiphospholipid antibodies (aPL): detection and clinical significance]

Phospholipid-binding antibodies are heterogeneous immunoglobulins of G and/or M and/or A class which can be detected in association with a variety of pathologies. However they can also occur in the absence of any clinical manifestations. Despite their paradoxical in vitro anticoagulant activity, phospholipid-binding antibodies, either primary or secondary, are frequently associated with venous and/or arterial thrombotic events. Hence, their detection has to be performed in several major clinical situations, cerebral attack, myocardial infarction, recurrent fetal loss, deep vein thrombosis ... Their course has to be controlled at least every six months. Since the incidence of phospholipid-binding antibodies in auto-immune pathologies is high, immunological disorders should also be considered. As yet there is no standardized assay of phospholipid-binding antibodies, either functional with respect to their anticoagulant activity, or immunological (ELISA). It is not established whether they possess an own pathogenic potential or appear as a secondary response following cellular alterations known to be thrombogenic. However it has been suggested that they could participate in the disruption of the hemostatic balance towards procoagulant tendency resulting in thrombosis.     

Diagnosis of antiphospholipid syndrome

Antiphospholipid syndrome is a multisystem autoimmune disease, characterized by recurrent vascular thrombosis and/or pregnancy losses in the presence of persistently positive antiphospholipid antibodies. In clinical practice, testing for anticardiolipin antibodies and lupus anticoagulant is mandatory for the laboratory diagnosis of antiphospholipid syndrome. Identification of patients with antiphospholipid syndrome is important, as prophylactic anticoagulant therapy may prevent thrombosis from recurring, and treatment during pregnancy can improve fetal and maternal outcome.     

Anticoagulation during pregnancy

Venous thromboembolism (VTE) occurs infrequently but is a leading cause of illness and death during pregnancy and the puerperium. In the general population the incidence of pregnancy-associated VTE is approximately 1 in 1500 deliveries. The risk of VTE is five times higher in a pregnant than in a nonpregnant woman. Postpartum the VTE risk is even higher. Women with congenital abnormalities or persistent presence of antiphospholipid antibodies have an increased risk of VTE during pregnancy and the puerperium. Women with previous VTE have an approximately 3.5-fold increased risk of recurrent VTE during pregnancy. Heparin does not cross the placenta and is therefore the anticoagulant of choice. In case of acute thrombosis during pregnancy, treatment is performed in the same manner as for nonpregnant patients. There is an ongoing debate whether pregnant women with previous venous thrombosis should routinely receive prophylactic anticoagulation. Patients who have hereditary antithrombin deficiency, antiphospholipid antibodies, a combined abnormality, or a history of a severe thrombotic event (pulmonary embolism or extended deep vein thrombosis) should be advised to use prophylactic heparin during pregnancy, starting during the first trimester. Postpartum prophylaxis should be given to all women with an increased risk for VTE. A large body of evidence has been presented that hypercoagulability may cause recurrent abortions, stillbirth, and preeclampsia. There is no doubt that the antiphospholipid syndrome is strongly associated with fetal loss. The combination of heparin and aspirin significantly decreases the fetal loss rate during pregnancy and thus this is the treatment of choice in this patient group. Several studies indicate that women with recurrent miscarriage may benefit from heparin administration during pregnancy, however, data from controlled trials have not yet been published. In women with artificial heart valves, maternal and fetal complications are frequent despite anticoagulation, but oral anticoagulants can reduce the risk for maternal complications.     

Anticardiolipin antibodies in a patient with Crohn's disease and thrombosis.

Thrombosis is an uncommon though well recognized complication of inflammatory bowel disease, for which various coagulation alterations have been described as possible causes. Antiphospholipid syndrome (APS) is defined as the association of thrombosis, fetal loss and thrombocytopenia with anticardiolipin antibodies (aCL) and/or lupus anticoagulant (LA). We describe a case of a 21-year-old female with recurrent thrombosis associated with aCL who went on to develop Crohn's disease. Tissue typing done in this patient revealed the presence of the HLA-DR7, DRw53, which previous studies have shown to be found in increased frequencies in APS patients. To our knowledge, this is the first report of an association between these two clinical conditions and, in this particular case, aCL may be implicated in the thrombotic events.     

Fetal loss treatment in patients with antiphospholipid antibodies.

A group of seven young women with antiphospholipid antibodies, histories of recurrent fetal loss, and no live births is reported. Two patients had systemic lupus erythematosus, and the other five fulfilled criteria for the primary antiphospholipid syndrome. A false Venereal Disease Research Laboratory (VDRL) test was present in four of the patients, three had a previous episode of arterial or venous thrombosis, or both, and two had thrombocytopenia. Prednisone and acetylsalicylic acid were given, and monthly controls of lupus anticoagulant activity were carried out. The dose of acetylsalicylic acid was fixed while the dose of steroids was adjusted according to the degree of lupus anticoagulant activity. A fetal survival was obtained in 7/9 (78%) of the pregnancies. Three of the newborn infants had transitory lupus anticoagulant activity. A search for antiphospholipid antibodies should be carried out in patients with otherwise unexplained fetal losses, falsely positive VDRL tests, thrombosis, or thrombocytopenia as the treatment of such patients with prednisone and acetylsalicylic acid is highly effective.