Laboratory Evaluation of the Antiphospholipid Syndrome

[Indicators of homeostasis, inflammation and homocysteine in ischemic stroke in the young age]

AIM

To determine indicators of homeostasis, inflammation and homocysteine in the young-aged patients with ischemic stroke (IS) of different genesis in the subacute and chronic stages.

MATERIAL AND METHODS

Out of 218 patients with IS (mean age 34.7±8.7 years), 55 had stroke due to dissection of the inner carotid or the spinal artery, 28 due to cardioembolia, 38 due to antiphospholipid syndrome (APS), 16 due to cerebral arteritis; 85 patients were classified as having cryptogenic stroke, including 23 with noncerebral thrombosis (coagulopathy of unknown etiology) and 62 with no thrombosis. The control group included 28 healthy people matched for age and sex.

RESULTS

There were 1) an increase in von Willebrand factor and coagulation factor VIII as well as a decrease in plasminogen and an increase in plasmin-inhibitor in IS caused by thrombosis (APS, cardioembolia, coagulopathy of unknown etiology); 2) alterations in erythrocyte aggregation and deformity in cryptogenic stroke; 3) mild or moderate hyperhomocysteinemia, with the exception of patients with APS and arteritis. Linear regression analysis confirmed these relationships. Discriminant analysis identified the clusters of parameters characteristic of APS (an increase in (aPTT), plasminogen, blood sedimentation rate, C-reactive protein) and cardioembolia (decreased protein C and increased hematocrit).

CONCLUSION

The laboratory markers associated with cerebral thrombosis can be used for identification of a prothrombotic state as a cause of IS in the young age. Moderate hyperhomocysteinemia is a risk factor but not a cause of IS. The increase of inflammatory markers in APS suggests a role of infection in its development.

Anticardiolipin antibody and anti-beta 2 glycoprotein I antibody assays

Antiphospholipid syndrome (APS) is an autoimmune disease and is a risk factor for a number of clinical manifestations; the classic presentations include fetal death or thrombosis (arterial or venous thromboembolism), in the presence of persistently increased titers of antiphospholipid (aPL) antibodies. The actual cause of APS is unknown but thought to be multifactorial. The disease is characterized by the presence of a heterogenous population of autoantibodies against phospholipid-binding proteins. APS presents either in isolation with no evidence of an underlying disease or in concert with an autoimmune disease such as systemic lupus erythematosus or rheumatoid arthritis. The wide diversity in clinical presentation often causes difficulty in identifying and treating patients and therefore a concise laboratory report containing interpretative comments is required to provide needed guidance to the clinician. For a diagnosis of APS to be made both clinical and laboratory classification criteria must be met. Laboratory testing to identify aPL antibodies includes lupus anticoagulant (liquid-based clotting assays) and immunological solid-phase assays (usually enzyme-linked immunosorbent assay formats) for IgG and/or IgM anticardiolipin (aCL) antibodies and anti-beta 2 glycoprotein I (β2-GPI) antibodies. Other autoantibodies, such as those directed against anionic phospholipids, can also be assayed; however they are not of clinical significance. Participation in a quality assurance program and an in-depth technical and clinical understanding of testing for aPL antibodies are required, as methods are limited by poor robustness, reproducibility, specificity, and standardization. Testing is further complicated by the lack of a "gold standard" laboratory test to diagnose or classify a patient as having APS. This chapter discusses the clinical and laboratory theoretical and technical aspects of aCL and anti-β2GPI antibody assays.

An approach to the patient with retiform purpura

Retiform purpura consists of branching purpuric lesions caused by a complete blockage of blood flow in the dermal and subcutaneous vasculature. The differential diagnosis for retiform purpura is broad, including vasculitides of the small and medium vessels as well as microvascular occlusion due to thrombotic, infectious, and embolic phenomena. Determining the etiology of this important dermatologic sign can be a diagnostic challenge; however, an organized approach can improve the speed and accuracy of diagnosis and identify an effective treatment. This review focuses on early recognition, evaluation, and treatment of hospitalized patients with retiform purpura. Specifically, vasculitis, protein C and S deficiencies, heparin necrosis, warfarin necrosis, antiphospholipid antibody syndrome, disseminated intravascular coagulation, cryoglobulinemia, calciphylaxis, and cholesterol embolization syndrome will be discussed in detail. These conditions are commonly seen in consultative dermatology and can have multiorgan involvement, complicated laboratory evaluation, and long-term therapeutic implications.

An open label, non-randomized, prospective clinical trial evaluating the immunogenicity of branded enoxaparin versus biosimilars in healthy volunteers

INTRODUCTION

Compositional variations among biosimilar enoxaparin could lead to a differential immunogenic response between these preparations.

METHODS

Enoxaparin (Clexane, n = 110) and a biosimilar version (Cutenox, n = 110) were administered to healthy volunteers in Brazil, 40 mg subcutaneous (SQ), daily, for 10 days. Blood was collected at baseline, days 1 and 10, and analyzed for antiheparin/PF4 antibody (AHPF4 antibodies) titers and subtypes by enzyme-linked-immunosorbent serologic assay (ELISA).

RESULTS

Low-molecular-weight heparin (LMWH) treatment resulted in AHPF4 antibodies generation, with differences on day 10 (P < .05). Antibody subtyping (immunoglobulin [Ig] G, IgA, IgM) demonstrated different profiles between LMWH with statistical significance for IgG (Clexane 10 = 0.21 ± 0.06, Cutenox 10 = 0.28 ± 0.10, P < .0001) and IgA (Clexane 10 = 0.15 ± 0.02, versus Cutenox 10 = 0.13 ± 0.02, P < .0001) on day 10, with a significant drug effect (P < .0001) and significant time by drug interaction (P = .0009). All antibody titers were stated in terms of optical density (OD) units.

CONCLUSION

LMWHs immunogenic potential varies to generate AHPF4 antibodies and subtypes and cross-reactivity with preformed antibodies. Such parameters may be useful in defining the biosimilar LMWHs bioequivalence. Future studies evaluating the immunogenicity of biosimilar drugs are warranted.

Automated mixing studies and pattern recognition for the laboratory diagnosis of a prolonged activated partial thromboplastin time using an automated coagulation analyzer

INTRODUCTION

The objective of this study was to explore whether an automated coagulation analyzer could be applied to normal plasma mixing studies for the assessment of blood samples showing a prolonged activated partial thromboplastin time (APTT).

MATERIALS AND METHODS

Ten laboratory staff members performed normal plasma mixing studies and evaluated plasma samples using 3 different methods: (1) manual dilution and analysis, (2) manual dilution and automatic analysis with STA-R®, and (3) automatic dilution and analysis with the Coapresta® 2000 (CP2000). The time from the start of the analysis to the generation of the result plots and the plasma volumes required were determined. We analyzed patient plasma samples showing a prolonged APTT using the CP2000, and the result plots were categorized into 3 curve patterns based on the area ratio values: the inhibitor type (convex pattern), deficiency type (concave pattern), and suspicious inhibitor type (approximately straight pattern).

RESULTS

When pooled patient plasma was used, the same patterns were obtained from normal plasma mixing studies using the 3 different methods. The time required to complete the mixing studies and the plasma volumes required were 28.2 ± 2.4 min and 350 μL for manual analysis, 23.2 ± 2.1 min and 875 μL for STA-R(®), and 8.5 +/- 0.1 min and 175 μL for CP2000, respectively. Of 31 patient samples, 9 were categorized into the inhibitor type, 15 were categorized into the deficiency type, and 7 were categorized into the suspicious inhibitor type.

CONCLUSIONS

The CP2000 analyzer is applicable to the laboratory diagnosis of a prolonged APTT using pattern recognition, as it requires a shorter time to complete mixing studies and a smaller plasma volume in comparison with manual analysis.

Neurological manifestations of antiphospholipid syndrome

BACKGROUND

Neurologic disorders are among the most common and important clinical manifestations associated with the antiphospholipid syndrome (APS). It is characterized by diverse neurological manifestations. These include stroke, transient ischaemic attack, Sneddon's syndrome, convulsions/epilepsy, dementia, cognitive deficits, headaches/migraine, chorea, multiple sclerosis-like, transverse myelitis, ocular symptoms and Guillain-Barré syndrome.

MATERIAL AND METHODS

We review the latest data about neurologic disorders and APS.

RESULTS

In patients under 45 years of age, 20% of strokes are potentially associated with APS. Our study group recently reported a correlation between primary APS and peripheral neuropathy. Only one study investigated the occurrence of peripheral neuropathy in patients diagnosed with PAPS through electrophysiological study and showed alterations in 35% of patients. The mechanism of nervous system involvement in APS is considered to be primarily thrombotic. However, other mechanisms have been described, such as antiphospholipid antibodies that bind to the neural tissue, deregulating their functions and having an immediate pathogenic effect.

CONCLUSIONS

This review summarizes the latest data regarding the clinical aspects, radiological and therapeutic of major neurologic manifestations associated with antiphospholipid antibodies.

Laboratory identification of lupus anticoagulants

Lupus anticoagulants (LA) are acquired autoantibodies that can cause antiphospholipid syndrome. LAs prolong phospholipid-dependent coagulation tests, acting as nonspecific inhibitors that are neutralized in the presence of excess phospholipid. However, there is no gold standard test and the testing is influenced by a number of variables. This article summarizes laboratory testing for LAs, with particular focus on technical issues and limitations of testing. Am. J. Hematol. 2009. (c) 2009 Wiley-Liss, Inc.