Progression of antiphospholipid antibody syndrome to catastrophic antiphospholipid antibody syndrome acutely with cessation of antithrombotic therapy.

Catastrophic antiphospholipid antibody syndrome (CAPS) is a serious condition that is often unrecognised with a high mortality. Cessation of anticoagulation in antiphospholipid antibody syndrome (APS) can have devastating consequences with progression to CAPS. Making a diagnosis of APS can however be challenging because of the evolving diagnostic criteria and difficulty in confirming thromboses. Management of these patients can also be complex, especially in those with coexistent thrombocytopenia. New potential treatments are emerging targeted on the immunomodulation of APS rather than just prevention of thrombosis. This article aims to highlight these diagnostic and management difficulties by reporting and discussing three cases of APS with progression to CAPS following cessation of anticoagulation, one with fatal consequences, with confirmation of CAPS on autopsy, and two with successful treatment and outcomes.

Fatigue, muscle strength and vitamin D status in women with systemic lupus erythematosus compared with healthy controls.

Recent studies have demonstrated an inverse relationship between vitamin D levels and fatigue in systemic lupus erythematosus (SLE). The aims of this study were to evaluate proximal muscle strength, fatigue and vitamin D levels in women with SLE compared with healthy controls and to investigate relationships between these factors in a cohort of women with SLE. Forty-five women (24 SLE, 21 healthy controls) participated. Primary outcome measures were the fatigue severity scale (FSS), isometric muscle strength of dominant limbs using hand held dynamometry, two functional tests--the 30-second chair stand test and the 1-kg arm lift test, with vitamin D status measured using 25(OH)D. Overall 25(OH)D levels were 68.4 (22.4) nmol/L with no difference between SLE and control groups. There was a statistically and clinically significant difference in fatigue, 1-kg arm lift, 30-second sit to stand, knee extension, hip flexion, hip abduction, shoulder flexion and grip strength in the SLE group compared with the control group (p < 0.05). In the SLE group FSS was moderately correlated with both functional measures (1-kg arm lift r = -0.42, 30-second chair stand r = -0.44, p < 0.05). However, no statistically significant correlation between dynamometry measures and fatigue was evident. There was no association between fatigue and 25(OH)D level (r = -0.12). In summary, women with SLE were weaker and demonstrated reduced physical function and higher fatigue levels than healthy controls. Fatigue was related to physical function but not vitamin D status or maximal isometric strength in vitamin D replete individuals with SLE.

Immune reconstitution inflammatory syndrome manifesting as development of multiple autoimmune disorders and skin cancer progression.

We report the case of a 56-year-old man with the rare autoimmune pathologies of alternating hypothyroidism and hyperthyroidism due to thyroid-stimulating hormone receptor antibodies, and rheumatoid arthritis as manifestations of a human immunodeficiency virus-related immune reconstitution inflammatory syndrome. The patient also developed overt progression of a pre-existing skin malignancy that may also be related. This case highlights immune reconstitution syndrome as an important differential diagnosis following antiretroviral therapy commencement, and that a high index of suspicion should be maintained for this rare but important cluster of conditions. Furthermore, the patient's genetic predisposition to autoimmunity provides helpful insights into the pathogenesis of these disorders.

Test-retest reliability of hand-held dynamometry and functional tests in systemic lupus erythematosus.

The aim of this study was to evaluate the test-retest reliability and determine the degree of measurement error of tests of isometric muscle strength and upper and lower limb function in women with systemic lupus erythematosus (SLE). Twelve women with SLE (age 39.8 ± 10 years) were assessed on two occasions separated by a 7-10-day interval. Strength of six muscle groups was measured using a hand-held dynamometer; function was measured by the 30-s sit to stand test and the 30-s 1 kg arm lift. Relative reliability was estimated using the intraclass correlation coefficient (ICC), model 2,1 (ICC2,1). Absolute reliability was estimated using standard error measurement and the minimal detectable difference was calculated. All ICCs were greater than 0.87. Muscle strength would need to increase by between 18% and 39% in women with SLE to be 95% confident of detecting real changes. The functional tests demonstrated a systematic bias between trials. This study demonstrates that hand-held dynamometry in SLE can be performed with excellent reliability. Further work needs to be completed to determine the number of trials necessary for both the 30-s sit to stand and 30-s 1 kg arm lift to decrease the systematic bias.

Beta2-glycoprotein I: target antigen for 'antiphospholipid' antibodies. Immunological and molecular aspects.

It has become clear that beta2-glycoprotein I (beta2GPI) is the most common and best-characterised antigenic target for 'antiphospholipid' (aPL) autoantibodies. These antibodies preferentially bind beta2GPI that has been immobilised on anionic phospholipid membranes or certain synthetic surfaces. These surfaces appear to act by increasing antigen density to allow binding of intrinsically low-affinity anti-beta2GPI autoantibodies. Binding of beta2GPI in fluid phase is weak and requires high concentrations of beta2GPI. Our understanding of the pathophysiology of the 'Antiphospholipid' Syndrome (APS) has increased exponentially with the number of studies into the interactions of aPL antibodies and beta2GPI.

Current insights into the "antiphospholipid" syndrome: clinical, immunological, and molecular aspects.

Advances in defining the target antigen(s) for the autoantibodies in the APS highlight the inadequacies of the current classification of these autoantibodies into anticardiolipin and LA antibodies. The discovery that beta 2GPI is the target antigen for the autoantibodies detected in solid-phase immunoassays has opened a number of areas of research linking these autoantibodies to atherogenesis and thrombus formation. Although the role of beta 2GPI in the regulation of blood coagulation in unclear, current evidence suggests that anti-beta 2GPI antibodies interfere with its "normal" role and appear to promote a procoagulant tendency. The expansion of research in this area and the diversity of the clinical manifestations of patients with APS have resulted in the inclusion of molecular biologists and pharmaceutical companies joining immunologists, hematologists, rheumatologists, obstetricians, neurologists, vascular surgeons, and protein and lipid biochemists in attempting to understand the pathophysiology of this condition. Although the published literature may result in conflicting results and introduce new controversies, developing standardized laboratory methods and extrapolation of in vitro experimental results to the vivo situation will advance our understanding of the regulation of the immune system and its interaction with normal hemostatic mechanisms. Since the authors' last review in 1991, the study and understanding of the pathophysiology of APS have evolved from lipid biochemistry to molecular techniques that may eventually provide specific therapies for the clinical manifestations of this condition. Although current treatment has improved the morbidity associated with this condition, especially in improving pregnancy outcomes, future therapies, as outlined in this review, may specifically address the biological abnormalities and have fewer side effects. Better diagnostic tools, such as magnetic resonance imaging with perfusion studies, will allow the study of the true incidence and prevalence of vascular flow changes/tissue ischemia and infarction associated with aPL antibodies and help determine treatment and prophylaxis for APS patients. APS is still the only hypercoagulable condition where both arterial and venous beds can be affected independently or in the same individual.

Heterogeneity of lupus anticoagulant (LA) antibodies: LA activity in dilute Russell's Viper Venom Time and dilute Kaolin Clotting Time detect different populations of antibodies in patients with the "antiphospholipid" syndrome.

"Antiphospholipid" (aPL) antibodies comprise two main groups of antibodies, lupus anticoagulant (LA) antibodies and "anticardiolipin" (aCL) antibodies which can be separated by certain chromatographic techniques. In this study we analysed the plasma of 10 patients with aPL antibodies, and were able to demonstrate that in four patients with both clotting test reactivities, the dilute Russell's Viper Venom Time (dRVVT) activity can be separated from the dilute Kaolin Clotting Time (dKCT) reactivity by using a polyacrylamide-immobilised phosphatidylserine column but not with phospholipid liposomes. The differential reactivity of the autoantibodies in this patient population is not due to binding to beta2GPI, prothrombin or protein C in solid-phase immunoassays. Hence LA antibodies detected in different phospholipid-dependent clotting tests detect different populations of antibodies in some APS patients and the routine detection of LA antibodies should be performed with at least two clotting tests looking at different coagulation reactions.

Anti-beta 2-glycoprotein I autoantibodies from patients with the "antiphospholipid" syndrome bind to beta 2-glycoprotein I with low affinity: dimerization of beta 2-glycoprotein I induces a significant increase in anti-beta 2-glycoprotein I antibody affinity.

"Antiphospholipid" autoantibodies are associated with arterial and venous thrombosis, recurrent fetal loss, and thrombocytopenia. At present, the best-characterized antigenic target for these autoantibodies (or Abs) is the phospholipid-binding protein beta2-glycoprotein I (beta2GPI). These Abs bind beta2GPI only in the presence of negatively charged phospholipids or microtiter polystyrene plates that have been specially treated to give the surface a negative charge. To determine whether the binding of these Abs to beta2GPI on negatively charged surfaces is dependent on increased density or neo-epitopes formed as a consequence of a conformational change on beta2GPI, we generated mutants of beta2GPI by site-directed mutagenesis and assessed the binding characteristics of anti-beta2GPI Abs to these mutants. Our results demonstrate that mutant F307*, which spontaneously forms significant dimerization, is bound best by all the anti-beta2GPI Abs in an anti-beta2GPI ELISA using irradiated polystyrene microtiter plates. In addition, these Abs bound mutant F307* coated onto standard polystyrene microtiter wells in the absence of phospholipid, whereas there was minimal binding with wild-type and mutant F307*/C288A, which formed minimal dimerization. Affinity-purified anti-beta2GPI Abs from patients with the antiphospholipid syndrome demonstrated significantly higher binding affinity for mutant F307* in fluid phase than for wild-type or mutant F307*/C288A of beta2GPI. These results demonstrate that autoantibody binding to beta2GPI is intrinsically of low affinity and that the binding is dependent on the density of the Ag and not on neo-epitope formation.

Anti-beta2-glycoprotein I and anti-prothrombin antibodies in patients with the 'antiphospholipid' syndrome: immunological specificity and clotting profiles.

Lupus anticoagulant (LA) antibodies have been shown to be directed to protein-phospholipid complexes. In this study, we report on LA antibodies from patients with the 'antiphospholipid' syndrome (APS), that are directed to prothrombin and beta2-glycoprotein I, but not to the complexes of these plasma proteins to anionic phospholipids. The anti-prothrombin antibodies studied had different reactivities in two clotting assays: the dilute Russell's viper venom time (dRVVT) and the dilute kaolin clotting time (dKCT). Anti-prothrombin and anti-beta2-glycoprotein I (anti-beta2GPI) antibodies, affinity-purified from one patient with APS were not cross-reactive and had different effects in the dRVVT and dKCT clotting tests. Polyclonal anti-prothrombin antibodies, affinity-purified on a prothrombin column, from two patients with prothrombin reactivity in their plasma, have affinity constants to prothrombin of 104 and 192 nM. The patient with affinity-purified antibodies to prothrombin and beta2GPI, had affinity constants to prothrombin and beta2GPI, respectively, of 192 nM and 3030 nM, respectively. LA antibodies are a heterogeneous population of antibodies that have different immunological specificities and clotting test reactivities in different patients.

Human beta 2-glycoprotein I binds to endothelial cells through a cluster of lysine residues that are critical for anionic phospholipid binding and offers epitopes for anti-beta 2-glycoprotein I antibodies.

Beta 2-Glycoprotein I (beta 2GPI) is a phospholipid-binding protein recognized by serum autoantibodies from the anti-phospholipid syndrome both in cardiolipin- and beta 2GPI-coated plates. We found that: 1) recombinant wild-type beta 2GPI bound to HUVEC and was recognized by both human monoclonal IgM and affinity-purified polyclonal IgG anti-beta 2GPI anti-phospholipid syndrome Abs; and 2) a single amino acid change from Lys286 to Glu significantly reduced endothelial adhesion. Double and triple mutants (from Lys284,287 to Glu284,287, from Lys286,287 to Glu286,287, and from Lys284,286,287 to Glu284,286,287) completely abolished endothelial binding. A synthetic peptide (P1) spanning the sequence Glu274-Cys288 of the beta 2GPI fifth domain still displayed endothelial adhesion. Another peptide (P8), identical with P1 except that Cys281 and Cys288 were substituted with serine residues, did not bind to HUVEC. Anti-beta 2GPI Abs, once bound to P1 adhered to HUVEC, induced E-selectin expression and up-regulated IL-6 secretion. Control experiments conducted with irrelevant Abs as well as with the P8 peptide did not show any endothelial Ab binding nor E-selectin and IL-6 modulation. Our results suggest that: 1) beta 2GPI binds to endothelial cells through its fifth domain; 2) the major phospholipid-binding site that mediates the binding to anionic phospholipids is also involved in endothelial binding; 3) HUVEC provide a suitable surface for beta 2GPI binding comparable to that displayed by anionic phospholipids dried on microtiter wells; and 4) the formation of the complex between beta 2GPI and the specific Abs leads to endothelial activation in vitro.

beta 2-Glycoprotein I: target antigen for autoantibodies in the 'antiphospholipid syndrome'.

Antiphospholipid' (aPL) antibodies are of important clinical significance because of their association with thrombosis both arterial and venous, recurrent foetal loss, specific neurological sequelae like seizures and chorea, cardiac valvular abnormalities and thrombocytopenia. Traditionally these autoantibodies have been assayed using phospholipid (PL) dependent tests and are classified as lupus anticoagulants (LA) and anticardiolipin (aCL) antibodies based on the method of detection. The antibodies thus, had been thought to bind PLs but it has now become clear that the true antigens are PL-binding proteins. The major protein consistently found as the target antigen for these autoantibodies is beta 2-glycoprotein I (beta 2-GPI). Other candidate PL-binding proteins have also been investigated including prothrombin, protein C and protein S but thus far appear to play less important roles in the binding of these antibodies.

Monoclonal antibodies from NZW x BXSB F1 mice to beta2 glycoprotein I and cardiolipin. Species specificity and charge-dependent binding.

NZW x BXSB F1 mice develop a systemic autoimmune syndrome with various lupus-like manifestations. Male animals develop a degenerative coronary disease with myocardial infarction, resulting in death before 6 mo of age. The presence in these mice of anti-phospholipid Abs reacting with beta2-glycoprotein I may contribute to the pathogenesis of the cardiovascular lesions. beta2-glycoprotein I, a plasma protein implicated in various aspects of the coagulation pathway, is also the target of autoantibodies in humans with the anti-phospholipid syndrome. We obtained several mAbs from NZW x BXSB F1 mice that were selected for binding to cardiolipin. Two mAbs are specific for beta2-glycoprotein I and display a species-dependent pattern with preferential reactivity to mouse beta2-glycoprotein I. The other mAbs display charge-mediated interactions with anionic phospholipids in the absence of beta2-glycoprotein I. The analysis of the V region sequences of the mAbs suggests that cationic residues in the H chain complementarity-determining region 3 are important for their phospholipid reactivity. The structural features of the V(H)-D-J(H) junctions of these mAbs further support the view that an increased frequency of unusual V(D)J rearrangements directly contributes to the development of murine autoimmunity.

The role of beta 2-glycoprotein I in the antiphospholipid syndrome.

Antiphospholipid antibodies were originally thought to bind negatively-charged (anionic) phospholipids. Current evidence suggest that the target antigen is considerably more complex and includes beta 2-glycoprotein I, a phospholipid-binding plasma protein. Our understanding of the pathophysiology of the antiphospholipid syndrome has increased exponentially with a number of studies into the interactions of antiphospholipid antibodies and beta 2-glycoprotein I.

Immunology of antiphospholipid antibodies and their interaction with plasma proteins.

'Antiphospholipid' (aPL) antibodies are of clinical importance because of their strong association with vascular thrombosis, recurrent pregnancy loss, thrombocytopenia and other clinical manifestations like livedo reticularis, chorea and cardiac valvular disease. While aPL antibodies have traditionally been thought to be directed against negatively-charged (anionic) phospholipids current evidence suggests that these autoantibodies recognise protein-phospholipid complexes or the proteins themselves. A number of candidate proteins have been investigated with the two most extensively researched being beta 2-glycoprotein I and prothrombin.

Laboratory detection of antiphospholipid antibodies.

'Antiphospholipid' (aPL) antibodies are a heterogenous group of autoantibodies that are now considered to be directed mainly to plasma proteins or protein-phospholipid complexes. Standardisation of assays for anticardiolipin (aCL) antibodies and lupus anticoagulants (LA) have been fraught with difficulty despite numerous attempts to perform this by International Standardisation Workshops and Committees.

Epitope specificity of monoclonal anti-beta 2-glycoprotein I antibodies derived from patients with the antiphospholipid syndrome.

beta 2-Glycoprotein I (beta 2GPI) has been identified as a cofactor in the recognition of the phospholipid Ag cardiolipin (CL) by anticardiolipin Ab (aCL) purified from patients with autoimmune diseases. However, there is considerable controversy as to the exact nature of the epitopes to which these Abs are directed. mAb derived from patients with the antiphospholipid syndrome bound to CL only in the presence of beta 2GPI. Synthetic peptides that span the fifth C-terminal domain of beta 2GPI supported the binding of one of the mAbs to CL in a beta 2GPI-free system. These peptides possessed the phospholipid binding sequence Cys281-Lys-Asn-Lys-Glu-Lys-Lys-Cys288. Three of the mAbs bound to beta 2GPI that had been adsorbed on gamma-irradiated microtiter plates. Binding to beta 2GPI was inhibited in a dose-dependent manner by the peptides from the carboxyl-terminal end of beta 2GPI and soluble beta 2GPI, indicating that the mAb bound to peptides and beta 2GPI in free solution. Thus, mAbs derived from patients with the antiphospholipid syndrome have specificity for epitopes on the fifth domain of beta 2GPI. Our results support the idea that beta 2GPI acts as a primary Ag for these Abs.

Increased levels of leukemia inhibitory factor in synovial fluid from patients with rheumatoid arthritis and other inflammatory arthritides.

OBJECTIVE: To examine synovial fluid (SF) from patients with arthritis, for the presence of the cytokine leukemia inhibitory factor (LIF). METHODS: SF from 152 subjects was examined for LIF, using a radioreceptor competition assay. RESULTS: LIF was present at concentrations of 1-43 ng/ml in the SF of 23% of patients with rheumatoid arthritis (RA) or other inflammatory or infectious arthritides but in only 1 of 29 patients with osteoarthritis (P < 0.01). In the RA patients, the SF LIF concentration correlated significantly with the peripheral blood white blood cell count (WBC) (P < 0.05) and the SF WBC count (P < 0.01), but not with other clinical or radiologic parameters of disease activity or progression. CONCLUSION: LIF is implicated as a potential mediator of the local or systemic inflammatory response or the joint destruction seen in inflammatory arthritis.