Antiphospholipid Syndrome: An Overview

This paper reviews antiphospholipid syndrome (APS), also known as Hughes syndrome which is a potentially life-threatening autoimmune disorder where the material part produces antibodies directed toward phospholipids and phospholipid-binding proteins. Diagnosis of this syndrome relies upon both clinical and laboratory criteria. Laboratory testing used for diagnosing APS includes coagulation assays for the detection of lupus anticoagulant (LA) and enzyme-linked immunosorbent assay (ELISA) for antiphospholipid antibody (APL) detection.

ABBREVIATIONS: APL = antiphospholipid antibodies; APS = antiphospholipid syndrome; APTT = activated partial thromboplastin time; ??^sub 2^-GPI = beta^sub 2^-glycoprotein I; dRVVT = dilute Russell's viper venom time; ELISA = enzyme-linked immunosorbent assay; Ig = immunoglobulin; KCT = kaolin clotting time; LA = lupus anticoagulant.

INDEX TERMS: antiphospholipid syndrome; antiphospholipid antibodies; laboratory techniques and procedures; lupus anticoagulant.

Clin Lab Sci 2006;19(3):144

APS, which was first described by the agency of Graham Hughes in 1983,1 is an auto-immune disorder that is characterized through the presence of APL, arterial and/or venous thrombosis, and repeated pregnancy los The syndrome is categorized as primary or secondary based upon whether it occurs alone (primary APS) or in the nearness of other diseases (secondary APS), primarily autoimmune disorders like as systemic lupus erythematosus.2 Patients with APS progres seldom to the catastrophic form of this disorder which is characterized by the agency of multiple organ infarcts transcending to multiple organ failure within days. The syndrome is more commonly noted in young to middle-aged adults and exhibits a female predominance.3 APL can be met with in connective tissue disorders, infectious disease states like as syphilis and AIDS, and may be medicine induced. They can also offer incidentally in healthy individuals and as a arise APL are considered clinically significant solitary when present in APS.4

Mechanisms of pathogenicity

In APS, APL consist of LA, anticardiolipin antibodies, and anticardiolipin antibodies that recognize specific target atoms such as beta^sub 2^-glycoprotein I (??^sub 2^-GPI), prothrombin, protein C protein s and annexin V.5,6 The exact mechanism in which these antibodies cause or advance thrombosis is not known; however, it is clear that multiple mechanisms are involved. single study was aimed at determining the IgG subclass distribution of anticardiolipin and anti-p2-GPI antibodies and the clinical manifestations of each subclass. This research found that different IgG subclasses (anti-??^sub 2^-GPI IgG^sub 2^ anti-??^sub 2^-GPI IgG^sub 3^ anticardiolipin IgG^sub 2^) which differ in their effector functions, were associated with the same syndrome manifestations (arterial and/or venous thrombosis and fetal loss)7 A next to the first study investigating the genetics of ??^sub 2^-GPI, a naturally occurring anticoagulant, base that ??^sub 2^-GPI concentration varied in healthy populations and level identified ??^sub 2^-GPI congenitally deficient siblings. Interestingly, the siblings did not exhibit a history of thrombotic episodes. This leads to the conclusion that thrombosis in patients with anti-??2-GPI antibodies can not be explained barely by the secondary ??^sub 2^-GPI deficiency caused by dint of circulating APL.8

It is theorized that these antibodies bind small room surface phospholipids or phospholipid-binding proteins, thereby interfering with the clotting proces or promoting it. more [i]or[/i] less of the proposed mechanisms of pathogenicity are stimulation of platelet function, interference with the function of phospholipid-binding proteins, and activation of endothelial cells6 APL stimulate platelet function by the agency of binding to their phospholipid surface membranes. During platelet activation, there is an increase in in all senses of anionic phospholipids on the external small room membrane, making them more reactive to APL and creating a repetitive period of activation and spontaneous aggregation.1 ??^sub 2^-GPI and annexin V are serum phospholipidbinding proteins that are believed to be naturally occurring circulating anticoagulants. one as well as the other bind endothelial cell surface anionic phospholipids rendering them unreactive for coagulation reactions. APL directed at these proteins interfere with dieir anticoagulant abilities and be derived in a procoagulant state. Activation of endothelial small rooms by APL causes upregulation of the expression of adhesion monads (E-selectin, intracellular adhesion molecule-1 and vascular confined apartment adhesion molecule-1) and secretion of cytokines (interleukin-1, and interleukin-6) promoting adhesion and inflammation.1,6 Obstetric complications of APS include fetal death, pregnancy-induced hypertension, intrauterine-growth retardation and fetal heart arrest and are a result of thrombosis in the vasculature of the uterus and placenta.5,9

Clinical features

As previously stated, APS is characterized through arterial and venous thrombosis and consequently clinical features of the syndrome can vary widely and can involve any organ a whole The features for both primary and secondary APS are identical. Features involving the central nervous combination of parts to form a whole most commonly include stroke, and les commonly cerebral dysfunction that can range from poor concentration or forgetfulness to relentless dementia. The more important cardiac features of APS include manifestations of coronary artery disease (atherosclerosis and myocardial infarction) and valve disease which not absents as vegetative masses and valvular wall thickening. Hypertension, at hand in 70% of patients, caused through renal and/or pulmonary involvement is a major clinical feature of APS. Manifestations that cause hypertension include pulmonary embolism, renal artery thrombosis and intrarenal vascular lesions. Skin features greatest in quantity frequently include livido reticularis, a purple-mottl fishnet pattern of the skin, and skin gatherings