Current status and implications of autoimmune antiphospholipid antibodies in relation to thrombotic disease

This review briefly describes the development of the concepts of antiphospholipid antibody and of antiphospholipid syndrome. It focuses on the two main antigenic targets, beta2 glycoprotein I and prothrombin. An excessive production of natural antibodies rather than an immune response to exogenous antigen is proposed as pathogenetic for the development of these antibodies. The review attempts to explain how some of these antibodies are anticoagulant in vitro yet prothrombotic in vivo. The final section discusses when to test for such antibodies, how to test and how to consider treatment of patients with the antiphospholipid syndrome.

Selection of thrombogenetic antiphospholipid antibodies in cerebrovascular disease patients

BACKGROUND AND PURPOSE

The association between anticardiolipin antibodies (aCL) and thrombosis is well recognized, but its role as an independent risk factor for stroke is not. The study's aim was to investigate the presence of antiphospholipid antibodies (aPL) and ischemic vascular events by using both traditional means the estimation of aCL and glycoprotein (beta(2)GP1) antibodies. Additionally both aCL/beta(2)GP1 and aPLmix/beta(2)GP1 antibodies were measured. The measurement of these two antibodies was determined by using as target antigens, either cardiolipin alone or a mixture of different phospholipids coated with human beta(2)GP1 in order to select only the autoimmune antibodies. One hundred and twenty-two consecutive patients with first-ever acute ischemic cerebrovascular event were included and compared with controls. The presence of aCl in patients (20.5 %) and controls (14.7 %) was not significantly different (p = 0.1). The presence of abeta(2)GP1 (6.5 % versus 4.9 %, p = 0.7) was also not significant, while there were associations for aCL/b2GP1 13.9 % versus 4.9 % (p = 0.02) and aPLmix/beta(2)GP1 15.6 % versus 4.9 % (p = 0.01). These latter tests seem to be useful in assessing the autoimmune and therefore the thrombogenetic antibodies.

Antiphospholipid antibodies in 57 children and adolescents with systemic lupus erythematosus

OBJECTIVE

To investigate the frequencies and behavior of antiphospholipid antibodies in 57 children and adolescents with systemic lupus erythematosus.

METHODS

Anticardiolipin antibodies were investigated by ELISA and lupus anticoagulant antibodies by the international tests recommended. The antiphospholipid antibodies analyses were performed in frozen samples (mean of 5.3 samples per patient obtained during a mean follow-up period of 3 years and 7 months) and on blood samples collected between January 1997 and November 1998 (mean of 2.5 samples per patient during a 2-year follow-up period).

RESULTS

The frequencies of antiphospholipid antibodies (anticardiolipin and lupus anticoagulant) were similar in the samples collected prospectively and in the frozen samples (retrospective study): 63.2% and 75.4% respectively. Positivity for these antibodies fluctuated during the follow-up period and was not associated with any clinical or laboratory parameters of lupus erythematosus, including autoantibodies and also including disease activity and/or severity scores.

CONCLUSIONS

The frequencies of antiphospholipid antibodies in children and adolescents with lupus erythematosus were similar to those observed in adults. The positivity fluctuated during the follow-up and was not correlated with clinical and/or laboratory disease parameters.

Antiphospholipid antibodies: discovery, definitions, detection and disease

Antiphospholipid antibodies (aPL) are immunoglobulins of IgG, IgM and IgA isotypes that target phospholipid (PL) and/or PL-binding plasma proteins. Detection of aPL in the laboratory is done currently by both immunoassays and functional coagulation tests. Convention defines aPL specificity in immunoassays according to the particular PL substrate present, for example aPS represents antiphosphatidylserine antibodies. This may be technically incorrect inasmuch as a particular PL may be responsible for binding and highly concentrating a specific plasma protein, the latter then becomes the target for the aPL. The binding of beta(2)GP-I (apolipoprotein H) to the negatively charged PL, cardiolipin (CL) provides a good example of this circumstance. In contrast, aPL which specifically prolong coagulation times in in vitro are called lupus anticoagulants (LA). The precise PL target(s) of the aPL responsible for LA activities are unknown and often debated. The persistent finding of aPL in patients in association with abnormal blood clotting and a myriad of neurological, obstetrical and rheumatic disorders often compounded by autoimmune diseases has led to an established clinical diagnosis termed antiphospholipid syndrome (APS). The common denominator for these APS patients is the presence of circulating aPL on two or more occasions and the observation of events attributable to abnormal or accelerated blood clotting somewhere in vivo. The purpose of this review is to collect, collate, and consolidate information concerning aPL.

Relationship of interleukin-12 and interleukin-13 imbalance with class-specific rheumatoid factors and anticardiolipin antibodies in systemic lupus erythematosus

The aim of the study was to evaluate whether the imbalance between IL-12 and IL-13 serum levels, reflecting Th1/Th2 activity, is related to class-specific circulating rheumatoid factors (RF) and anticardiolipin (aCL) antibodies in SLE. Using ELISA we measured serum IL-12, IL-13, RF and aCL antibodies in 73 SLE patients and 20 healthy controls. The determination of IL-12/IL-13 ratio showed that IL-12 levels were above (group A), equal to (group B) or below (group C) IL-13 levels in 71.2%, 15.1% and 13.7% of SLE patients, respectively. IgM-RF levels were significantly higher in group C than in groups A ( P < 0.002) and B ( P < 0.019). Group C had also higher IgM-aCL levels than group A ( P < 0.04). No relationship between IL-12/IL-13 ratio and clinical or other laboratory parameters was found. It was concluded that the increased levels of both IgM-RF and IgM-aCL in patients with prevalent Th2 activity suggest that the predominance of Th2 over Th1 could drive autoantibody production in SLE patients.

Antiphospholipid syndrome with renal artery embolism: case report

Antiphospholipid syndrome is characterized by venous and arterial thrombosis. Antiphospholipid antibodies are essential to making the diagnosis. It may be a primary disorder or it may be secondary to a connective tissue disorder. Cardiac manifestations of this syndrome include both thrombotic and degenerative valvular disease. Systemic or pulmonary embolism, as well as intravascular thrombosis, is a significant cause of morbidity and mortality. We present a case of renal infarction in a woman with polymyalgia rheumatica and a positive test for antiphospholipid antibody.

Benign Degos' disease developing during pregnancy and followed for 10 years

Degos' disease, or malignant atrophic papulosis, is a rare and often fatal multisystem vasculopathy of unknown etiology. The cutaneous manifestations comprise erythematous papules, which heal to leave scars with a pathognomonic central porcelain-white atrophic area and a peripheral telangiectatic rim. Involvement of the gastrointestinal tract is observed in 50% of cases, with intestinal perforation being the most common cause of death. Other organ systems can also be affected; 20% of cases involve the central nervous system. Systemic manifestations usually develop from weeks to years after onset of skin lesions or, in rare instances, may precede skin lesions. In the patient with Degos' disease reported in this article, the characteristic skin lesions developed during pregnancy, a precipitating event not previously reported. She has survived an unusually long time (10 years) without visceral or neurological involvement, despite florid cutaneous lesions. Moreover, we could detect the presence of antiphospholipid antibodies, the significance of which are currently unclear. These observations therefore confirm that there may be a strictly cutaneous form of Degos' disease with a favourable prognosis.

The role of microvascular injury in the evolution of idiopathic pulmonary fibrosis

Interstitial lung disease compatible with idiopathic pulmonary fibrosis (IPF) developed in 19 previously healthy patients. Although interstitial and/or honeycomb parenchymal fibrosis was present in all, there were patchy areas of paucicellular septal capillary injury along with corroborative direct immunofluorescent evidence of a humorally mediated microvascular injury syndrome. Significantly elevated factor VIII levels were seen in 17 of 18 patients tested. Antiphospholipids were present in all 18 patients tested, comprising antibodies of phosphatidylethanolamine, beta-2 glycoprotein, phosphatidylcholine, and/or phosphatidylserine. Anti-Ro and/or anti-ribonucleoprotein (RNP) antibodies were seen in 4 patients. Serologic evidence of infection with cytomegalovirus (CMV) was found in 9 patients and parvovirus B19 (B19) in 9 patients; 1 patient was not tested. Molecular studies revealed B19 DNA in 6 of 6 B19-seropositive patients. In situ hybridization studies revealed CMV RNA in pulmonary cells in patients with serologic evidence of active CMV infection despite the absence of cytopathic changes typical of CMV infection. Antiphospholipid antibodies, antiendothelial cell antibodies, and/or endotheliotropic viral infections related to B19 and CMV may be of pathogenetic importance to the evolution of IPF. This report underscores the potential importance of microvascular injury in the evolution of IPF.

Anti-phospholipid antibodies and carotid-artery intima-media thickness in young survivors of myocardial infarction

BACKGROUND

Not all coronary events occur in young individuals with traditional risk factors. In recent years some authors have observed increased prevalence of elevated anti-phospholipid (aPL) antibodies in young patients with myocardial infarction. Also, thickening of the combined arterial intima-media thickness (IMT) of superficial vessels has been identified as an independent risk factor for both stroke and heart attack. The objective of our study was to assess possible association between aPL antibodies and carotid IM thickening in young survivors of myocardial

MATERIAL/METHODS

In a case control study we determined IgG and IgM antiphospholipid antibodies by enzyme-immunoassay, and IMT by ultrasonography in 50 male survivors of myocardial infarction under the age of 50, and compared them to 50 healthy controls.

RESULTS

Elevated aPL antibody levels (IgG>10 GPL; IgM>20MPL) were detected in 12 of 50 patients (24%) with MI and in 3 of 50 controls (6%). The mean level of aPL antibodies was significantly higher in the patients than in the controls (IgG 9.15+/-3.53 vs 7.69+/-2.98 GMP, p=0.04 and IgM 18.46+/-7.61 vs 12.14+/-5.05 MPL, p<0.01). Patients with MI had a significantly greater IMT than healthy controls (0.9 mm vs 0.6 mm; p<0.01). There was a correlation between aPL and IM thickening (r=0.31; p=0.01). Among coronary risk factors only hypertension (r=0.28; p=0.01) and smoking (r=0.41; p=0.01) showed a relationship with IMT.

CONCLUSIONS

The intima-media thickness of the carotid artery and elevated aPL antibodies are strongly associated with the risk of myocardial infarction in young patients.

Antiphospholipid antibody syndrome in a six-year-old female patient

PURPOSE

To report the first instance of primary antiphospholipid antibody (APA) syndrome in an otherwise healthy 6-year-old female patient with retinal venous thromboses.

DESIGN

Observational case report.

METHODS

A 6-year-old girl with poor vision in the left eye and preretinal hemorrhage underwent testing for infectious, autoimmune and embolic disease, diabetes, and hypertension. Testing for factor V Leiden and prothrombin G20210A mutations, homocysteine, anticardiolipin antibodies (ACAs), lupus anticoagulant, and functional assays for protein S, protein C, and antithrombin III were performed to detect a hypercoagulable state. No IRB approval was necessary.

RESULTS

Only a positive lupus anticoagulant and moderately elevated ACA IgG were found. The ACA IgG was moderately elevated on repeat testing 18 months later. Laser to nonperfused retina caused some regression of retinal neovascularization. Aspirin was recommended to reduce the risk of future thromboses.

CONCLUSIONS

Although uncommon, retinovascular thrombosis in children can occur in APA syndrome. Testing for ACA and lupus anticoagulant should be considered.

[Antiphospholipid antibodies in acute coronary syndrome]

The authors examined the presence of antiphospholipid antibodies in acute coronary syndrome. As their results show the frequency of antibodies against B2-glycoprotein I is significantly higher (14.4%) than the presence of these antibodies in a healthy control group (2%). Occurrence of antibodies against B2-glycoprotein I is much more higher than the occurrence of IgG- or IgM type antibodies against cardiolipin or lupus anticoagulant.

CONCLUSIONS

The authors emphasize the possible role of anti-B2-glycoprotein I antibodies in thrombotic process of acute coronary syndrome. The previous ischaemic stroke was significantly more frequent in those patients medical history in whose serums antibodies against B2-glycoprotein I were present, so the presence of this thrombophil factor in acute coronary syndrome points out the importance of secunder antithrombotic prevention.

The presence of antiphospholipid antibodies is not related to increased levels of annexin A5 in plasma

Annexin A5 has been proposed to be important for shielding of negatively charged phospholipids from blood, thereby preventing the binding of clotting factors. It has been suggested that antiphospholipid antibodies can disrupt the binding of annexin A5 from negatively phospholipid-containing surfaces, resulting in uncontrolled coagulation. If this hypothesis is correct, than the plasma levels of annexin A5 will be increased in patients with antiphospholipid antibodies. Therefore, we have measured plasma levels of annexin A5 of 175 patients with systemic lupus erythematosus (SLE), of which 104 had antiphospholipid antibodies and 23 patients had primary antiphospholipid syndrome. The annexin A5 levels were compared with the annexin A5 plasma levels measured in 23 patients with diabetes mellitus type 2 and 35 healthy volunteers. We found a significant increase of annexin A5 plasma levels in patients with SLE (median 6.7 ng mL(-1)) and primary antiphospholipid syndrome (median 7.1 ng mL(-1)) as compared to patients with diabetes mellitus type 2 (median 3.3 ng mL(-1)) and healthy volunteers (median 3.9 ng mL(-1)). However, no correlation was found with the presence of antiphospholipid antibodies or with a history of thromboembolic complications. Based on these observations, we conclude that displacement of annexin A5 from cellular surfaces by antiphospholipid antibodies is not a common mechanism in patients with antiphospholipid antibodies.

Inherited and acquired risk factors and their combined effects in pediatric stroke

The aim of this study was to identify hereditary and acquired risk-factors as they are related to the occurrence of stroke in children. We identified 21 children with stroke. A search of the Factor V Leiden mutation, the Factor II G20210A variant, and the thermolabile variant of methylenetetrahydrofolate reductase was performed in patients and in a control group (n = 115). We identified risk factors of acquired and/or hereditary nature for stroke in 19 of 21 children. Eleven children had three or more risk factors, seven had two risk factors, and one child had only one risk factor. We found three carriers (14.3%) of the Factor V Leiden mutation, two carriers (9.5%) of the Factor II G20210A variant, eleven (52.4%) thermolabile variant of methylenetetrahydrofolate reductase heterozygote carriers, and one (4.8%) homozygotes for this variant. Frequencies of the Factor V Leiden mutation and the Factor II variant were higher in patients than in controls, suggesting that these variants are associated with an increased risk of stroke in childhood. Homozygosity for the thermolabile variant of methylenetetrahydrofolate reductase was equally frequent amongst patients and controls. Our study confirms that stroke in children is commonly associated with a combination of multiple risk factors, both genetic and acquired, and that the Factor V Leiden mutation and the Factor II G20210A variant are predisposing factors for this situation.

Intracardiac thrombosis and mitral prosthesis dysfunction in systemic lupus erythematosus. A case report

Systemic lupus erythematosus (SLE) is an inflammatory disease characterized by deposition of autoantibodies and pathogenic immune complexes in the cells and tissues of an organism, causing lesions. The heart is one of the most frequently involved organs, valvar involvement being common (27%) and of great clinical importance. Some studies suggest that valvar involvement is associated with the presence of a specific autoantibody, the antiphospholipid antibody (aPL). In these circumstances, major complications may occur such as arterial or venous thrombosis, thrombocytopenia, repeated spontaneous abortions and presence of lupus anticoagulant antibody. Among the semiologic methods for cardiac evaluation, echocardiography is the main instrument for investigating the anatomical and functional involvement of the heart in the great majority of systemic diseases like SLE. We report the case of a patient with SLE and aPL syndrome who underwent surgery for mitral valve replacement with a biological prosthesis and died nine months later due to massive intracardiac thrombosis and prosthesis dysfunction.

Anticardiolipin antibody titre and plasma homocysteine level independently predict intima media thickness of carotid arteries in subjects with idiopathic antiphospholipid antibodies

This study evaluated whether IgG anticardiolipin antibody (aCL) titre and traditional risk factors for atherosclerosis bore any relationship to the intima media thickness (IMT) of carotid arteries of patients with idiopathic antiphospholipid antibodies (aPL). IMT was assessed by high-resolution sonography at the common carotid, carotid bifurcation and internal carotid in 42 (13 male, 29 female, mean age 31+/-10 years) aPL subjects, 29 with primary thrombotic antiphospholipid syndrome and 13 with persistence of aPL in the absence of any underlying disorder. In the same subjects the following were measured: plasma fibrinogen (FNG), von Willebrand factor (vWF), plasminogen activator inhibitor (PAI), homocysteine (HC), total cholesterol (CHO), triglycerides (TG), high density and low density lipoprotein (HDL and LDL), platelet numbers and aCL of IgG and IgM isotype. IMT of the internal carotid was greater in males than females (0.48+/-0.03 vs 0.39+/-0.01 mm, P=0.02). IMT of the carotid bifurcation was greater in thrombotic than nonthrombotic subjects (0.50+/-0.02 vs 0.42+/-0.02 mm, P=0.04). By simple regression, IMT of the common carotids correlated with age (P< 0.0001) IgG aCL titre (P=0.001), FNG (P=0.006), LDL (0.01), CHO (0.02) and PAI (P=0.02). IMT of the carotid bifurcation correlated with age (P=0.002), IgG aCL titre (P=0.0002), FNG (P=0.0001), HC (P=0.009), CHO (P=0.02), vWF (P=0.01) and number of thrombotic events (P=0.03). IMT of the internal carotids correlated with age (P=0.002), IgG aCL titre (P=0.0001), FNG (P=0.0008), PAI (P=0.002) and HC (P=0.01). By stepwise multiple regression analysis, IgG aCL titre independently predicted IMT at all carotid segments examined (P always <0.005). In addition, plasma FNG and HC also resulted independent predictors of IMT at the carotid bifurcation (P=0.001 and P<0.0001, respectively) and internal carotid (P=0.03 and P<0.0001, respectively). These data strongly support an atherogenic role for IgG aCL in patients with aPL. Measurement of plasma HC and FNG may help define aPL subjects at higher vascular risk who may require lowering of HC and FNG by vitamin and/or pharmacologic intervention.

A prospective cohort study determining the prevalence of thrombotic events in children with acute lymphoblastic leukemia and a central venous line who are treated with L-asparaginase: results of the Prophylactic Antithrombin Replacement in Kids with Acute Lymphoblastic Leukemia Treated with Asparaginase (PARKAA) Study

BACKGROUND

Thrombotic events (TEs) are serious secondary complications in children with acute lymphoblastic leukemia (ALL) who receive L-asparaginase (ASP) therapy; however, the prevalence of TEs has not been established. The primary objective of the Prophylactic Antithrombin Replacement in Kids with Acute Lymphoblastic Leukemia Treated with Asparaginase (PARKAA) Study was to determine the prevalence of TEs. The secondary objective was to detect any association of TEs with the presence of congenital or acquired prothrombotic disorders.

METHODS

Children with ALL were screened for TEs at the end of ASP treatment using bilateral venograms, ultrasound, magnetic resonance imaging, and echocardiography. Symptomatic TEs were confirmed by appropriate radiographic tests. All tests were read by a blinded central adjudication committee.

RESULTS

Twenty-two of 60 children had TEs, a prevalence of 36.7% (95% confidence interval, 24.4-48.8%). TEs were located in the sinovenous system of the brain in 1 patient, the right atrium in 3 patients, and the upper central venous system in 19 patients. TEs detected by venography resulted in 1) 25-100% occlusion, with 1 in 3 patients showing occlusion of > 75% of the greatest vessel dimension, and 2) the presence of collaterals in 60% of patients, with 40% categorized as major. No children with TEs were positive for factor V Leiden or prothrombin gene 20201A, and four of eight children with antiphospholipid antibodies had a TE.

CONCLUSIONS

The prevalence of TEs is exceedingly high in this population, and it is likely that the extent of occlusion is likely clinically significant. No trend was seen toward an association between TEs and the presence of congenital prothrombotic disorders. A trend was seen toward an association between TEs and antiphospholipid antibodies. Carefully designed clinical trials of primary prophylaxis for the prevention of TEs are required in this patient population.

Antiphospholipid antibodies in young women with and without oral contraceptive use

The role of thrombophilia in the elevated risk of thromboembolism during oral contraceptive use has been established. We performed a cross-sectional study among young women to survey the occurrence of antiphospholipid antibodies among users and non-users of oral contraceptives. Serum levels of immunoglobulin (Ig)G, IgA and IgM isotypes of anti-beta2-glycoprotein I and anticardiolipin antibodies were measured by validated enzyme-linked immunosorbent assay methods. Combining all types of antiphospholipid antibodies, pill-users had an elevated antibody titre more than twice as frequently as non-users (odds ratio, 2.3; 95% confidence interval, 1.1-5.1). The higher frequency of elevated antibody titre was related most commonly to IgG type anti-beta2-glycoprotein I antibodies. Oral contraceptive use increases the risk of elevated antiphospholipid antibody levels among asymptomatic young women.

Leg ulcer in Klinefelter's syndrome

Hypostatic ulceration of the legs is relatively uncommon in men. Recently, the hypothesis that recurrent ulceration in men may be associated with chromosomal abnormalities such as Klinefelter's syndrome is gradually being accepted. Herein, we describe a patient with Klinefelter's syndrome complicated by recurrent leg ulcers, in whom immunological disorders such as positive antinuclear factor, antiphospholipid antibodies and cryoglobulins without venous insufficiencies were demonstrated. Interestingly, these abnormalities of immune functions were normalized after the androgen replacement therapy for Klinefelter's syndrome, and his leg ulcers immediately recovered.