Antiphospholipid-protein antibodies: laboratory detection and clinical relevance

The Role of Cardiolipin and Mitochondrial Damage in Kidney Transplant

Chronic kidney disease (CKD) is highly incident and prevalent in the world. The death of patients with CKD is primarily due to cardiovascular disease. Renal transplantation (RT) emerges as the best management alternative for patients with CKD. However, the incidence of acute renal graft dysfunction is 11.8% of the related living donor and 17.4% of the cadaveric donor. Anticardiolipin antibodies (ACAs) or antiphospholipid antibodies (APAs) are important risk factors for acute renal graft dysfunction. The determination of ACA or APA to candidates for RT could serve as prognostic markers of early graft failure and would indicate which patients could benefit from anticoagulant therapy. Cardiolipin is a fundamental molecule that plays an important role in the adequate conformation of the mitochondrial cristae and the correct assembly of the mitochondrial respiratory supercomplexes and other proteins essential for proper mitochondrial function. Cardiolipin undergoes a nonrandom oxidation process by having pronounced specificity unrelated to the polyunsaturation pattern of its acyl groups. Accumulation of hydroxyl derivatives and cardiolipin hydroperoxides has been observed in the affected tissues, and recent studies showed that oxidation of cardiolipin is carried out by a cardiolipin-specific peroxidase activity of cardiolipin-bound cytochrome c. Cardiolipin could be responsible for the proapoptotic production of death signals. Cardiolipin modulates the production of energy and participates in inflammation, mitophagy, and cellular apoptosis. The determination of cardiolipin or its antibodies is an attractive therapeutic, diagnostic target in RT and kidney diseases.

Anticardiolipin Antibodies in Hemophiliac and Nonhemophiliac Patients with Chronic Hepatitis C

Anticardiolipin antibodies (ACA) have been de tected in a variety of infectious diseases, especially viral infec tions. ACA also have been described in human immunodefi ciency virus (HIV)-infected hemophiliacs. Recently the pres ence of ACA in hemophiliac and nonhemophiliac patients with chronic hepatitis C virus has been reported. We performed a case-controlled study to establish if ACA are present in hemo philia and if they are due to the hepatitis C infection; and to confirm the association between ACA and hepatitis C infec tions in nonhemophiliac patients. Anticardiolipin antibodies have been studied in the serum of 62 hemophiliacs with chronic hepatitis C virus and in the control group (70 hepatitis C- negative patients with hemophilia or other clotting disorders). ACA were positive in only three hepatitis C-positive hemo philiac patients and in three hepatitis C-negative patients with hemophilia or other coagulation defects (first control group). No significant statistical differences were found in the groups (OR = 1.1; 95% CI 0.2-7.4, p = .6). Sixteen of 111 nonhe mophiliacs with chronic hepatitis C were positive for ACA while in 100 matched hepatitis C-negative subjects (second control group) anticardiolipin antibodies were positive in 9 pa tients. ACA tended to be higher in hepatitis C-positive nonhe mophiliac patients than in the control group, but the difference between the two groups was not statistically significant (OR = 1.7, 95% CI 0.7-4.4, p = .3). ACA do not seem to be associ ated with the chronic hepatitis C virus.

Cardiovascular events in patients with antiphospholipid antibodies: strategies of prevention

Antiphospholipid antibodies are a heterogeneous group of auto-antibodies against phospholipids-binding proteins. The antiphospholipid syndrome is an autoimmune disorder characterized by the clinical association of antiphospholipid antibodies with a condition of hypercoagulability that can affect any blood vessel. Involvement of larger vessels, such as arteries or veins, manifests in the form of thrombosis or thromboembolism, whereas involvement of small vessels manifests as thrombotic micro-angiopathy. The antiphospholipid syndrome is also characterized by the presence of recurrent fetal loss. Patients who are persistently positive for antiphospholipid tests, and who have an arterial thrombosis or venous thrombosis history, are at increased risk of recurrence. Oral anticoagulant therapy is the mainstay of treatment for the thrombotic manifestations of the syndrome. Therapy with anticoagulant drugs should be long-term. On the other hand, although the thromboembolic potential of antiphospholipid antibodies has been well documented, there is still no general consensus on the prophylactic treatment of antiphospholipid antibodies carriers who have never developed vascular/obstetric manifestations. The effect of primary prophylaxis in antiphospholipid antibodies positive individuals is not well known and no evidence-based recommendations exist for thrombosis prevention in these individuals. However, the presence of risk factors for thrombosis increases the risk of first event of antiphospholipid antibodies positive patients. In conclusion, there is still much to learn on primary prophylaxis of asymptomatic antiphospholipid antibodies carriers. Hopefully, evidence-based guidelines will be available in the future.

Anticardiolipin antibodies in pathogenesis of infertility

Background/Aim. Antiphospholipid syndrome (APS) is an autoimmune disorder clinically characterized by arterial or venous thrombosis and/or specific obstetric complications and presence of antiphospholipid antibodies (aPL) in the serum. It occurs in 0.3% of pregnant women, while 1% of them have two spontaneous abortions. The aim of this study was to analyze the frequency of biphospholipid antibodies in pregnant women with recurrent spontaneous abortions. Methods. We analyzed 60 pregnant women who had two or more recurrent miscarriages. The control group included 60 healthy pregnant women. We analyzed titres of anticardiolipin (aCL) IgG and/or IgM with high titres (> 20 U/mL), lupus anticoagulant (LAC) antibodies and anti-beta-2 glycoprotein (b2-GP1) IgG as well as parameters of coagulation status of pregnant women. Results. Analyzing Spearman's rank correlation coefficient in a group of affected patients, we noticed a slightly positive correlation of lupus anticoagulants (LAC) with aCL antibodies of both classes, while the correlation with b2GP1 IgG was negative. Both classes of aCL antibodies and antib2GP1 IgG were in a discrete positive correlation with the given variables. In the control group, there was a lack of consistency in correlation of the study variables with LAC-aCl IgG, compared to the affected patients, and there was a standard negative coefficient of correlation with anti-b2GP1 IgG. The correlation ratio of anti-b2GP1 IgG was negative for all studied test parameters. Analysis of hemostatic parameters showed a statistically significant difference in the concentration of fibrinogen (p < 0.01) and thrombocyte count (p < 0.05) between the study and the control group of pregnant women. Lower mean values of fibrinogen (2.90 ? 0.45 g/L) and lower thrombocyte count [(179.20 ? 6.00) ? 109] were found in the study group of pregnant women with secondary infertility compared to the mean values of fibrinogen (3.60 ? 0.55 g/L) and thrombocyte count [(236.05 ? 5.10) ? 109] in the control group. Activated partial thromboplastin time and prothrombin time were statistically significantly prolonged (p < 0.05) in pregnant women with spontaneous abortions compared to controls, suggest anticoagulant activity. Conclusion. In pregnant women with spontaneous abortions compared to healthy pregnant women slightly positive correlation of LAC with aCL antibodies of both classes, as well as a positive correlation of aCL antibodies with antib2GP1 IgG exist. On the other hand, hemostatic parameters values suggest an anticoagulatnt status in the blood of pregnant women with spontaneous abortions.

Pulmonary embolism due to internal jugular vein thrombosis without an indwelling catheter

A 65-year-old man who had undergone retropubic prostatectomy for prostate adenocarcinoma presented with sudden dyspnea and chest pain. Contrast-enhanced multi-slice computed tomography (MSCT) revealed thrombi in the left internal jugular vein (IJV) and in branches of the right pulmonary artery. Ultrasonography showed that the thrombus which occluded the left IJV was hypoechoic and mobile. After beginning anticoagulant therapy, he again presented with dyspnea and transient hypotension. MSCT and ultrasonography showed that the IJV thrombus had moved and caused a new embolism of the left pulmonary artery branch. This is a rare case of a patient who experienced non-catheter-related thrombosis of the IJV.

Interaction of beta2-glycoprotein 1 with phosphatidylserine-containing membranes: ligand-dependent conformational alterations initiate bivalent binding

Beta2-glycoprotein 1 (beta2GP1), a 50 kDa serum glycoprotein that binds anionic phospholipid-containing membranes, plays a regulatory role in physiology and pathology. The protein is a member of the short consensus repeat (SCR) superfamily containing four typical repeating domains and an aberrant fifth domain constructed into an SCR-like core at the C-terminus. To investigate the contribution of the individual domains to the binding of beta2GP1, a series of sequential domain-deleted recombinant protein fragments were generated and assessed for their interaction with PS-containing vesicles. Spectral analyses of lipid binding-dependent alterations in tryptophan emission spectra revealed that the (single) tryptophan residues of the individual domains underwent binding-dependent conformational alterations. Depending on the ionic strength, some domains moved from polar to nonpolar environments, while others moved from less polar to more polar environments. Analysis of a series of acrylamide quenching and resonance energy transfer experiments indicated that the binding of N-terminal domain 1 to PS membranes exists in two, ionic strength-dependent, conformations. At low ionic strengths, domain 1 bound to the vesicles and induced their precipitation and/or aggregation. At physiologic ionic strengths, domain 1 detached from the membrane surface while the remaining domains maintained their association with the membrane. Under these conditions, membrane-bound conformationally altered domain 1 projects away from the membrane surface, enabling it to interact with other proteins and/or cell surface ligands or receptors.

Predictive value of persistent versus transient antiphospholipid antibody subtypes for the risk of thrombotic events in pediatric patients with systemic lupus erythematosus

Study objectives were to determine, in children with systemic lupus erythematosus (SLE), (1) the association of antiphosholipid antibody (APLA) subtypes with thrombotic events (TEs) and (2) the predictive value of persistent versus transient antibodies for TEs. This is a cohort study of 58 SLE children in whom lupus anticoagulants (LAs), anticardiolipin antibodies (ACLAs), anti–β2-glycoprotein-I (anti–β2-GPI), and antiprothrombin (anti-PT) were assessed on at least 2 occasions (more than 3 months apart). Antibodies were classified as persistent (positive on at least 2 occasions) or transient (positive once). Outcomes were symptomatic TEs confirmed by objective radiographic tests identified retrospectively and prospectively. Seven of the 58 patients (12%) had 10 TEs; 5 patients had TEs during prospective follow-up. Persistent LAs showed the strongest association with TEs (P < .001). Persistent ACLAs (P = .003) and anti–β2-GPI (P = .002) were significantly associated with TEs; anti-PT (P = .063) showed a trend. Persistent or transient LAs and anti–β2-GPI showed similar strength of association, while ACLAs and anti-PT were no longer associated with TEs. Positivity for multiple APLA subtypes showed stronger associations with TEs than for individual APLA subtypes because of improved specificity. Lupus anticoagulant is the strongest predictor of the risk of TEs; other APLA subtypes provide no additional diagnostic value. Anticardiolipin antibodies and anti-PT require serial testing because only persistent antibodies are associated with TEs.

Prevalence of thrombophilia and catheter-related thrombosis in cystic fibrosis

Venous thrombosis in children and young adults is frequently associated with predisposing conditions and with an indwelling catheter or totally implantable venous access device (TIVAD). These systems are commonly used for the delivery of antibiotic therapy in patients with cystic fibrosis (CF). We reviewed our CF center's history of catheter-related events over 13 years and prospectively investigated the presence of risk factors for thrombosis in 66 children and adults with CF (age, 3-38 years; 32 females). Five thrombotic events had occurred in 4 patients, 2 of whom carried the factor V Leiden mutation. Five asymptomatic patients were diagnosed with heterozygous mutations of the factor V or prothrombin gene. Functional activity of protein C was decreased in 13 subjects, with a correlation to impaired liver function. Protein S activity was abnormal in 20 patients and was related to CF genotype. Anti-phospholipid antibodies (APA) were present in 6 asymptomatic patients. A reinvestigation after 3 years confirmed protein S deficiency in 12 of 14 patients, while most abnormalities for protein C or APA were inconsistent. In conclusion, a thrombophilic state was detected in 53% of patients, and 2 out of 4 subjects with TIVAD-related thrombosis carried a genetic defect. It may thus be helpful to include a hemostatic evaluation in the clinical decision process for or against TIVAD insertion in eligible CF patients.

Lupus anticoagulans in patients with recurrent spontaneous abortion and secondary sterility

Antiphospholipid antibodies (lupus anticoagulans and anticardiolipine antibodies) are frequent cause of recurrent spontaneous abortion in patients with secondary sterility. Our aim was to evaluate the frequency of lupus anticoagulans antibodies in patients with recurrent abortions and to analyze their coagulation status relative to health (control) patients. We got the statistical significances (p < 0.05) in number of lupus anticoagulans positive women between the groups. Activated partial tromboplastin time and protrombin time are statistical significant (p < 0.05) higher in analyzed patients with recurrent abortion, which is in agreement of existing lupus anticoagulans activity. Detecting by the time, antiphospholipid antibodies and giving the anticoagulant therapy to the patients, the risk for abortion will be decreased.

Is the determination of anti-beta2 glycoprotein I antibodies useful in patients with venous thromboembolism without the antiphospholipid syndrome?

Anti-beta2-glycoprotein I (beta2GPI) antibodies are frequently found in patients with lupus anticoagulant (LA). To investigate the prevalence of antibeta2GPI antibodies and their clinical impact in patients with a history of venous thromboembolism (VTE) without LA/anticardiolipin antibodies (ACA), we studied 503 patients [128 (36.2%) men, median age 41 years (interquartile range, IQR 28-54 years)] with previous thrombosis. A group of 113 individuals without VTE [43 (38.1%) men, age 46.7 years (IQR 38-52 years)] served as a control group. Among 418 patients without LA/ACA, anti-beta2GPI-IgG levels were elevated in seven (1.7%), -IgM in 15 (3.6%) and -IgA in 14 (3.3%) cases; in 58 patients with ACA, anti-beta2GPI-IgG levels were elevated in two (3.4%), six (10.3%) and three (5.2%), and in 27 with LA, they were elevated in 18 (66.7%), 19 (70.4%) and 10 (37%) respectively. Thus, the prevalence of elevated anti-beta2GPI antibodies was not increased in patients without LA/ACA but was strongly associated with LA. Patients without ACA/LA who had a recurrent event did not have higher prevalence of elevated anti-beta2GPI-IgG, -IgM or -IgA antibodies than those without a recurrent event. Thus, elevated antibeta2GPI antibodies are not likely to be a predictor of recurrent events in patients without LA. We conclude that determination of anti-beta2GPI antibodies does not improve the clinical management of patients with a history of VTE without LA/ACA.

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.

Cutaneous arteritis presenting with hyperpigmented macules: macular arteritis

Macular arteritis is a novel form of cutaneous arteritis in which the primary lesion is a hyperpigmented macule. Traditional stigmata of cutaneous vasculitis such as palpable purpura and erythematous nodules are not present. The disease is asymptomatic and appears to follow an indolent course. Systemic involvement has not been observed.

Laboratory control of oral anticoagulant treatment by the INR system in patients with the antiphospholipid syndrome and lupus anticoagulant. Results of a collaborative study involving nine commercial thromboplastins

Because of the variable responsiveness of thromboplastins to lupus anticoagulants (LA), concerns have been raised about the validity of the prothrombin time-International Normalized Ratio (PT-INR) in monitoring oral anticoagulant treatment in patients with the antiphospholipid syndrome (APS) and LA. To date, few studies have been performed, numbers of patients investigated are relatively small and results are conflicting. We report on a multicentre study organized to investigate further this clinically relevant issue. Each of nine thrombosis centres was asked to collect plasma samples from patients with APS who were on oral anticoagulants (cases) and patients without APS who were on oral anticoagulants (controls). Nine thromboplastins (three human recombinant, one from human placenta and five from rabbit brain) were calibrated at the co-ordinating centre according to World Health Organization guidelines. Measurements of the INR and factor X amidolytic activity for all frozen plasmas were performed centrally. The numbers of patients investigated were 58 cases and 57 controls. Between-reagent variability of the INR was higher in cases [coefficient of variation (CV) = 12.4%] than in controls (CV = 6.7%), but this was because of one of the thromboplastins only (Thromborel R, human recombinant), which measured considerably higher INR values than the others in cases but not in controls. In conclusion, our data indicate that LA interference on the PT-INR measured with the majority of commercial thromboplastins is not enough to cause concern if insensitive thromboplastins, properly calibrated to assign them an instrument-specific International Sensitivity Index are used. New thromboplastins, especially those made of relipidated tissue factor, should be checked for their responsiveness to LA before they are used to monitor oral anticoagulant treatment in patients with APS.

The evaluation of clotting times in the laboratory detection of lupus anticoagulants

Although there is international consensus regarding the general principles of testing for lupus anticoagulants (LAs), no agreement exists as far as the analysis of the clotting time results is concerned. Twenty-nine laboratories participating in the Fifth International Survey of Lupus Anticoagulants (ISLA-5) reported the activated partial thromboplastin time (APTT)-based clotting times obtained on seven defined test samples and a normal plasma (NP) using the same two reagents with low and high phospholipid (PL) concentrations, respectively. These clotting times were used to analyse how various methods of calculating the results may influence the apparent sensitivity of LA tests. We found that the use of a separate screening test may lead to the exclusion of samples where the presence of LA would have been detected by a combined screening and confirmatory method. For instance, the dilute APTT (dAPTT) gave a sensitivity of 53.5% (screening test), while the calculation of a ratio between the clotting times obtained with two different PL concentrations gave a sensitivity of 68.1% (confirmatory test). The normalisation of results by dividing with the corresponding results of NP increased the apparent sensitivity. The screening test ratio between dAPTT results of test samples and NP gave a sensitivity of 84.7%. The normalised ratio between the clotting times obtained with the two reagents (lupus ratio, LR) gave a sensitivity of 95.1%. We conclude that when testing for LA, all samples should be tested with both low (screening procedure) and high (confirmatory procedure) PL concentrations. These two clotting times should be evaluated in relation to each other and to the corresponding results obtained with a reference plasma (normalisation).

Low plasma levels of vitamin B(6) are independently associated with a heightened risk of deep-vein thrombosis

BACKGROUND

Elevated plasma levels of total homocysteine (tHcy) before and after an oral methionine load (PML) are associated with an elevated risk of deep-vein thrombosis (DVT). We investigated whether plasma levels of B vitamins that are involved in Hcy metabolism are associated with an elevated risk of DVT.

METHODS AND RESULTS

We compared 397 cases with previous DVT with 585 matched healthy controls. The plasma levels of folate, vitamin B(12), vitamin B(6,), and fasting and PML tHcy were measured. The ORs for DVT associated with high (>95th percentile) fasting levels and PML increases of tHcy were 2.1 (95% CI, 1.2 to 3.4) and 2.4 (95% CI, 1.5 to 3.9) after adjustment for established risk factors for DVT. Fasting plasma levels and PML increases in tHcy correlated negatively with vitamin levels. The crude OR for folate levels in the lowest quartile compared with the highest was 1.5 (95% CI, 1.1 to 2.1), and that for B(6) levels in the lowest and second quartiles compared with the highest was 1.5 (95% CI, 1.0 to 2.1). However, after adjustment for established risk factors and fasting and PML tHcy, the ORs for B(6) levels in the lowest and second quartiles only remained statistically significant (lowest quartile: OR, 1.8; 95% CI, 1.2 to 2.8; second quartile, OR, 1.9; 95% CI, 1.3 to 2.9).

CONCLUSIONS

High fasting and PML tHcy and low vitamin B(6) plasma levels are associated with an elevated risk for DVT independently of established risk factors for DVT. The association of low vitamin B(6) levels with the risk for DVT is independent of fasting and PML tHcy levels.

Oxidized low-density lipoprotein and autoimmune antibodies in patients with antiphospholipid syndrome with a history of thrombosis

The prevalence and clinical significance of plasma oxidized low-density lipoprotein (oxLDL) and antibodies against oxLDL (anti-oxLDL) were evaluated in patients with antiphospholipid syndrome (APS). OxLDL and IgG anti-oxLDL were determined by enzyme-linked immunosorbent assay in plasma samples from 80 patients with APS. Positive values (mean + 3 SD) for oxLDL and anti-oxLDL were found in 21 (26%) and 19 (24%) of 80 patients with APS, respectively These values were significantly higher than those in healthy subjects. Levels of oxLDL and anti-oxLDL antibodies in subgroupings of patients with APS who had experienced thrombotic events were compared. There were significant differences among the groups for the levels of both oxLDL and anti-oxLDL antibodies. Pairwise comparisons between the groups yielded similar but not identical results. There was a significant, positive correlation between levels of plasma oxLDL and anti-oxLDL. These results suggest that elevated levels of plasma oxLDL and anti-oxLDL may be risk factors and potential markers for thrombosis, especially for arterial thrombotic events, in patients with APS.

Left ventricular assist system recipients exposed to bovine thrombin preparations have a higher frequency of antiphospholipid antibodies than nonexposed recipients

After left ventricular assist system (LVAS) placement, recipients often develop antiphospholipid antibodies (aPL) that are associated with thrombosis. Fibrin glue containing a bovine thrombin preparation is used routinely in LVAS placement surgery. We investigated whether exposure to the thrombin preparation is responsible for stimulating aPL development in LVAS recipients. Pre-LVAS and weekly post-LVAS sera from six fibrin glue-exposed LVAS recipients and five nonexposed recipients were tested by enzyme-linked immunosorbent assay for IgG, IgA, and IgM anti-phosphatidylserine (aPS), anticardiolipin (aCL), anti-phosphatidylethanolamine (aPE), and anti-phosphatidylcholine (aPC). Fibrin glue exposed recipients developed a significantly greater number of aPL than the nonexposed recipients (24 vs. 8; p = 0.0069). In particular, a higher frequency of IgG aCL (6/6 vs. 1/5; p = 0.015) and IgG aPE (4/6 vs. 0/5; p = 0.045) were noted. Exposure to the bovine thrombin component of fibrin glue seems to stimulate aPL development in LVAS recipients.

Laboratory Investigation of Thrombophilia

Until recently, laboratory diagnosis of thrombophilia was based on investigation of the plasmatic anticoagulant pathways to detect antithrombin, protein C, and protein S deficiencies and on the search for dysfibrinogenemia and anti-phospholipid antibodies/lupus anticoagulants. More recently, laboratory investigations have been expanded to include activated protein C (APC) resistance, attributable or not to the presence of the factor V Leiden mutation; hyperprothrombinemia attributable to the presence of the prothrombin gene mutation G20210A; and hyperhomocysteinemia attributable to impairment of the relevant metabolic pathway because of enzymatic and/or vitamin deficiencies. All of the above are established congenital or acquired conditions associated with an increased risk of venous and, more rarely, arterial thrombosis.

Testing is recommended for patients who have a history of venous thrombosis and should be extended to their first-degree family members. Because most of the tests are not reliable during anticoagulation, it is preferable to postpone laboratory testing until after discontinuation of treatment.

Whenever possible, testing should be performed by means of functional assays. DNA analysis is required for the prothrombin gene mutation G20210A. Laboratory diagnosis for anti-phospholipid antibodies/lupus anticoagulant should be performed by a combination of tests, including phospholipid-dependent clotting assays and solid-phase anti-cardiolipin antibodies. Hyperhomocysteinemia can be diagnosed by HPLC methods or by fluorescence polarization immunoassays.

Spectrum of antiphospholipid antibodies (aPL) in patients with cerebrovascular disease

BACKGROUND

The association of stroke and antiphospholipid antibodies (aPL) other than anticardiolipin antibodies (aCL) is not well documented.

OBJECTIVE

To report the distribution of aCL, antiphosphatidylethanolamine (aPE), and antiphosphatidylserine (aPS) aPL among patients with symptomatic cerebrovascular disease evaluated by our Stroke Service at Indiana University Hospital from January 1997 to November 1999.

METHODS

We retrospectively reviewed medical records from 1997 to 1999 at Indiana University Hospital for all patients with symptomatic cerebrovascular disease using the International Statistical Classification of Diseases, 9th Revision, (ICD-9) codes. We identified patients with elevated titers of aPL. Sera from these patients were obtained within the first 30 days of the index event. We included only those patients for whom the serum samples were tested in a single laboratory by an in-house enzyme-linked immunosorbent assay (ELISA) for immunoglobulin G (IgG) immunoglobulin A (IgA) and immunoglobulin M (IgM) aCL, aPE, and aPS. We examined the clinical presentation, stroke risk factors, associated rheumatologic disorders, and distribution of aPL specificity and isotype.

RESULTS

Thirty-four of 185 patients, 26 women (76%), with a mean age of 46 years, and 8 men (24%) with a mean age of 46 years, had aPL. Nine patients had transient ischemic attacks (TIA), 25 suffered strokes, 23 had ischemic infarcts, and 2 had hemorrhagic infarcts (1 had a superior sagittal sinus thrombosis with bilateral hemispheric hemorrhagic infarcts, and one had bilateral hemorrhagic infarcts associated with systemic lupus erythematosus [SLE]). Six patients had SLE. The most common stroke risk factors were cigarette smoking (38%) and arterial hypertension (26%). Approximately two thirds (60%) of patients had a single positive aPL finding: aPE in 35%, aCL in 18%, and aPS in 6%. Multiple specificities were seen in 40%. IgA was the only aPL antibody isotype detected in 26% of the patients, IgG was the lone isotype in 24%, and IgM alone in 12%. Multiple aPL isotypes were detected in 38% of patients. Five patients (15%) presented with aPE IgA as the exclusive aPL.

CONCLUSION

In our series, aPE was the most frequent finding in stroke patients who were suspected to have an associated aPL syndrome. These specific types of aPL may be present relatively often in stroke patients and are often not assessed. Further studies are needed to determine how specific these aPL are in stroke versus other acute illnesses and versus healthy controls, and how these aPL are associated with stroke risk.

Acquired activated protein C resistance is associated with lupus anticoagulants and thrombotic events in pediatric patients with systemic lupus erythematosus

Acquired activated protein C resistance (APCR) has been hypothesized as a possible mechanism by which antiphospholipid antibodies (APLAs) cause thrombotic events (TEs). However, available evidence for an association of acquired APCR with APLAs is limited. More importantly, an association of acquired APCR with TEs has not been demonstrated. The objective of the study was to determine, in pediatric patients with systemic lupus erythematosus (SLE), whether (1) acquired APCR is associated with the presence of APLAs, (2) APCR is associated with TEs, and (3) there is an interaction between APCR and APLAs in association with TEs. A cross-sectional cohort study of 59 consecutive, nonselected children with SLE was conducted. Primary clinical outcomes were symptomatic TEs, confirmed by objective radiographic tests. Laboratory testing included lupus anticoagulants (LAs), anticardiolipin antibodies (ACLAs), APC ratio, protein S, protein C, and factor V Leiden. The results revealed that TEs occurred in 10 (17%) of 59 patients. Acquired APCR was present in 18 (31%) of 58 patients. Acquired APCR was significantly associated with the presence of LAs but not ACLAs. Acquired APCR was also significantly associated with TEs. There was significant interaction between APCR and LAs in the association with TEs. Presence of both APCR and LAs was associated with the highest risk of a TE. Protein S and protein C concentrations were not associated with the presence of APLAs, APCR, or TEs. Presence of acquired APCR is a marker identifying LA-positive patients at high risk of TEs. Acquired APCR may reflect interference of LAs with the protein C pathway that may represent a mechanism of LA-associated TEs. (Blood. 2001;97:844-849)

Autoantibodies Associated with Rheumatic Diseases

The identification of circulating autoantibodies contributes to the correct diagnosis as well as to the follow-up of rheumatic diseases. Some autoantibodies are even included in diagnostic and classification criteria for these types of autoimmune diseases. There are several relatively specific screening and identification methods for the measurement of autoantibodies available. The type of assay crucially influences the diagnostic value of the parameters. In general, routine laboratories should prefer enzyme immunoassays (ELISA) using well characterized antigens, although ELISA tests tend to produce more false-positive and true weakly positive results, which reduce their positive predictive value. Therefore one should be aware that laboratory results can only be properly interpreted when there is a correlation with the clinical situation and when the limitations of the technologies used for autoantibody identification have been taken into consideration. A diagnostic algorithm consisting of screening and identification steps should be established by each laboratory in order to create a rational, evidence-based and cost-effective basis for the diagnosis of rheumatic diseases.

Elevated anti-annexin V antibody levels in antiphospholipid syndrome and their involvement in antiphospholipid antibody specificities

To clarify the involvement of annexin V (ANX) in antiphospholipid antibody (APA) specificities, we studied antiANX antibodies (aANX) using 2 kinds of enzyme-linked immunosorbent assay plates (plain and gamma-irradiated) and anti-beta 2-glycoprotein I antibodies (a-beta 2GPI) in 53 patients with antiphospholipid syndrome (APS). The incidence of aANX IgG-positive results in the autoimmune APS group was significantly higher than that of healthy control subjects. However, we could not demonstrate a significantly higher incidence in the infection- or drug-induced group. Nor could we find an increased incidence of IgM isotype. When the 2 plates were compared, the discrepancies of positivity were demonstrated in both isotypes. We speculated that these discrepancies between the plate surfaces were attributed to the altered antigenicity of ANX. Although positivity of a-beta 2GPI was associated significantly with clinical manifestations, no significant associations were demonstrated between the incidence of aANX-positive results and clinical manifestations. We inferred that the involvement of aANX in the pathogenic mechanism of APS is unlikely.

Use of the dilute Russell viper venom time (dRVVT): its importance and pitfalls

Antiphospholipid antibodies (APA) are now recognized as the most common cause of acquired thrombophilia. These antibodies may lead to thrombosis in both arterial and venous sites. Lupus anticoagulants (LA) are the most significant risk factor among the various APAs. The detection of LAs remains challenging to most laboratories. Multiple screening tests are recommended (e.g. APTT, dilute PT and dRVVT). The dRVVT is one of the most important screening procedures. In many instances, commercially available dRVVT systems include a screening reagent with low PL concentration and a confirmatory product with high PL concentration. There are a number of commercially available dRVVT test systems. These reagents vary in phospholipid origin and concentration as well as source of Russell viper venom (RVV). It is imperative for laboratories to be well informed regarding reagent composition and laboratory performance.

Antiphospholipid antibodies in children without and in adults with and without thrombophilia

Antiphospholipid antibodies (APAs) are considered risk factors in patients with thromboembolic diseases. Although the incidence of such acquired coagulation disturbances in adults are well described, only few data exist for children. Therefore, in a first step to collect new data we analyzed the presence of different APAs in 202 consecutive children and compared them with two groups of adults. The children screened for APA were exclusively those who did not have any thromboembolic complications or a tendency for thrombophilia due to other underlying diseases such as systemic lupus or malignancy in their past or present medical history. Consecutive blood samples were evaluated from routine laboratory specimens. The two groups of adults comprised 200 patients after deep vein thrombosis and 200 patients without thromboembolic events that served as controls. Four lupus anticoagulant (LA) screening tests were determined: the dilute Russell's viper venom test; a lupus anticoagulant-sensitive activated partial thromboplastin time reagent; a second lupus-sensitive activated partial thromboplastin time; and the Kaolin clotting time. Furthermore, three different antiphospholipid antibodies ELISA assays against cardiolipin (ACA), beta2-glycoprotein I, and phosphatidyl-serine, were determined. The children had a much higher prevalence for LA than did the adults. On the other hand, their values for ACA were significantly lower than in adults with a history of thromboembolism. Findings in children were similar to the normal adult group. This has to be taken into account when evaluating children with thromboembolic diseases.

Value of prothrombin fragment 1.2 (F 1.2) in the diagnosis of stroke in young patients with antiphospholipid antibodies

The presence in the serum of antiphospholipid antibodies (aPL) is associated with venous and arterial thrombosis. This observation has led to the search for these antibodies in young patients with ischemic neurologic syndromes. However, 1% to 5% of healthy people may be found to have circulating aPL without necessarily being at increased risk of thromboembolism. Thus, the finding of APLA in a patient with cerebral ischemia does not necessarily provide an explanation for the etiology of the clinical syndrome. The aim of this study was to determine whether the presence of aPL in young patients with stroke or transient ischemic attacks represents a possible cause of hypercoagulability as defined by ongoing thrombin formation with resultant elevation of prothrombin fragment 1.2 (F1.2) levels. This was a retrospective, case-control study involving 57 subjects. Twenty-seven patients had a recent cerebrovascular ischemic event--either TIA or a stroke. Fifteen were positive for aPL, and 12 were aPL-negative. Thirty subjects, matched for age and sex with no history of cerebrovascular disease, served as controls. Of this group, 20 were aPL-positive and 10 were aPL-negative. Causes of hypercoagulability other than aPL were excluded by laboratory testing. A positive test for aPL was repeated after a 6-week interval and two positive tests were required for a patient to be regarded as being aPL-positive. Levels of F1.2 were measured by an ELISA technique. There was a significant difference (p < 0.05) in the mean F1.2 levels between the aPL-positive group with a history of cerebrovascular disease (mean F1.2 = 2.3733) and each of the other study groups. There was no statistically significant difference between any of the other study groups. Our findings suggest that F1.2 levels are elevated in young patients with cerebrovascular syndromes who have aPL and in whom other causes of hypercoagulability and atherosclerotic vascular disease are absent. Elevated F1.2 in these patients may be a potential marker of the hypercoagulable state associated with aPL.

High levels of antiphospholipid antibodies are associated with cytomegalovirus infection in unrelated bone marrow and cord blood allogeneic stem cell transplantation

Antiphospholipid antibodies (APA) are a family of autoimmune and alloimmune immunoglobulins recognizing protein-phospholipid complexes in in vitro laboratory test systems. These antibodies have been associated with several conditions (malignancies, autoimmune diseases, infections, use of drugs); moreover, a syndrome capable of inducing thromboembolic disease has recently been associated with the presence of these antibodies. The aim of this prospective study was to investigate the levels of APA in subjects affected by haematological malignancies undergoing allogeneic haematopoietic stem cell transplantation (ASCT). Between March 1996 and December 1997, 32 patients undergoing ASCT were studied prospectively until day +180 from transplant. The mean values of IgG and IgM anticardiolipin antibodies (ACA) increased in recipients of stem cells from anunrelated donor, and a statistically significant difference inACA IgG mean value between unrelated and related transplanted patients was demonstrated between days +95 and +180. All of the subjects who received stem cells from an unrelated donor had APA levels higher than the mean normal value +3 SD vs. 35% of those receiving stem cells from a related donor (P < 0.01). The reason for such a difference may be a result of the different incidence in documented cytomegalovirus (CMV) infection in the two groups (83% vs. 23%; P < 0.01), as indicated by the significant correlation between APA positivity and CMV infection (P < 0.05). No relationship was found between APA, conditioning regimen and acute or chronic graft vs. host disease (GVHD). Moreover, we did not observe any thromboembolic disorder or veno occlusive disease (VOD).

Light-chain paraproteins with lupus anticoagulant activity

A patient with newly diagnosed multiple myeloma manifested by urine kappa light-chain excretion and a small monoclonal spike (0.4 g/dl), presented with lower extremity deep venous thrombosis. A preheparin plasma-activated partial thromboplastin time (aPTT) was prolonged at 68 sec (normal control 26-42 sec). Additional studies confirmed the presence of lupus anticoagulant activity in the serum: the modified Russell Viper Venom Time (MRVVT) was 73 sec (normal control 24-42 sec) and with a 50:50 mix of the patient's plasma and pooled normal plasma, the MRVVT remained prolonged. Kappa light chains (LC) were isolated from the patient's urine and their purity confirmed by electrophoresis and immunofixation using specific immunoglobulin antisera. The patient's LC mixed with pooled normal plasma demonstrated LA activity by in vitro clotting tests (plasma-activated partial thromboplastin time 62 sec, with normal control of 45 sec), MRVVT of 44 sec with normal control of 35 sec. Purified urinary kappa light chains from a control patient with multiple myeloma and normal clotting studies, failed to prolong either the plasma-activated partial thromboplastin time or the MRVVT. We hypothesize that kappa LC in our patient demonstrated LA activity, which was unique to these LCs. Paraproteins with LA activity, to date, have included only intact immunoglobulins (Ig). While intact Ig paraproteins have been reported to possess LA activity, this is the first report to our knowledge of light-chain paraproteins possessing similar activity and resulting in clinically evident thrombosis. Light chain paraproteins could serve as useful models for further study of the mechanisms of activity of acquired LA inhibitors.

Antiplatelet factor 4--heparin antibodies in patients with antiphospholipid antibodies

Antibodies directed against platelet factor 4-heparin are present in patients with heparin-induced thrombocytopenia (HIT). Additionally, it has been suggested that heparin can be an antigenic target of antiphospholipid antibodies (aPL). We investigated the presence of heparin-platelet factor 4-induced antibodies (HPIA) in 33 patients with aPL. There were 30 patients with lupus anticoagulant, 25 with anticardiolipin antibodies, 21 with anti-beta2 glycoprotein I, and 18 with antiprothrombin antibodies. 20 patients had a history of thrombosis and 19 had received heparin during the last 60 months. We found 7 (21.2%) who had HPIA; 5 of them also had anti-beta2 glycoprotein I antibodies. Four patients had severe thrombocytopenia and suspicion of HIT. Among them, two presented high positive HPIA results, one of them with positive platelet aggregation test. The third patient showed grey zone HPIA and borderline aggregation test and the fourth one had negative results. Among patients without a history of HIT, 2 who had never received heparin presented high positive, one a moderate positive, and one a grey zone HPIA result; all of them with negative aggregation tests. Five positive sera samples were incubated with cardiolipin liposomes in the presence of beta2 glycoprotein I, and whereas an inhibition greater than 50% was achieved in anticardiolipin and anti-beta2 glycoprotein I activities, HPIA results did not change. We demonstrate that HPIA could be frequently found in patients with aPL. They are responsible for HIT in some cases but can also be found in patients who have not received heparin. Whether they predispose patients with aPL to HIT is not known; nevertheless, a close follow-up of heparin treatment in these patients seems to be mandatory.

Induction of antiphospholipid antibodies by immunization with synthetic viral and bacterial peptides

We previously induced pathogenic antibodies against anionic phospholipids (PL) in experimental animals by immunization with lipid-free purified human beta2glycoprotein I (beta2GPI). We hypothesized that antiphospholipid antibodies (aPL) are induced by in vivo binding of foreign beta2GPI to self-PL, thus forming an immunogenic complex against which aPL antibodies are produced. If this hypothesis is true, other PL-binding proteins that are products of ubiquitous viral/bacterial agents may also induce aPL. To test this hypothesis, groups of NIH/Swiss mice were immunized with synthetic peptides of viral and bacterial origin that share structural similarity with the putative PL-binding region of beta2GPI. Compared with the control groups, animals immunized with the peptides produced significantly higher levels of aPL and anti-beta2GPI antibodies. These findings demonstrate that some PL-binding viral and bacterial proteins function like beta2GPI in inducing aPL and anti-beta2GPI production, and are consistent with a role for such viral and bacterial proteins in inducing aPL antibody production in humans.

Antiphospholipid antibodies are a risk factor for early renal allograft failure

BACKGROUND

Biopsy specimens of transplanted kidneys that fail to function reveal cellular infiltrates, infarcts, and thrombi. Because antibodies to phospholipids (aPA) and/or phospholipid-binding proteins have been associated with thrombosis, we asked whether aPA are a risk factor for early allograft failure.

METHODS

Final crossmatch sera from 56 patients with primary nonfunctioning renal allografts were tested for aPA. Serum from the next consecutive patient to undergo transplantation served as transplantation controls. Both groups were compared with aPA values obtained from testing 252 control individuals. The ELISA was designed to detect IgG, IgM, and IgA antibodies to phosphatidylserine, cardiolipin, and phosphatidylethanolamine.

RESULTS

Patients were evaluated based upon the aPA ELISA findings. aPA were present in 57% of the patients with early nonfunction renal allografts and 35% of the patients with functioning grafts (P=0.0234). aPA in previously hemodialyzed patients did not predict allograft failure or success (P=0.3766). In contrast, all nonhemodialysis patients who had aPA at the time of transplantation experienced early allograft failure (P=0.0022).

CONCLUSIONS

These data show that aPA are an important risk factor for early renal allograft failure. Furthermore, aPA-positive patients who have no history of hemodialysis are at the greatest risk. Pretransplantation aPA screening of renal transplant candidates forewarns of early graft failure and indicates which patients may benefit from anticoagulant therapy.

Increased incidence of antiphospholipid antibodies in left ventricular assist system recipients

BACKGROUND

Antiphospholipid antibodies are associated with thrombosis. Because thromboembolic complications are often observed in recipients of a left ventricular assist system, we questioned if antiphospholipid antibodies were present in these patients. We report results from 10 patients who received a Novacor left ventricular assist system.

METHODS

Serum samples were collected before left ventricular assist system placement and weekly thereafter until discharge after cardiac transplantation. Samples were tested for IgG, IgA, and IgM antiphosphatidylserine, anticardiolipin, and antiphosphatidylethanolamine using an enzyme-linked immunosorbent assay.

RESULTS

Development of phospholipid-binding plasma protein-dependent antiphospholipid antibodies was observed in 9 of the 10 patients. Before placement of the assist system, 3 patients had IgG antiphospholipid antibodies, and 9 were positive after placement. None had IgA antiphospholipid antibodies before placement, whereas 5 seroconverted for IgA after placement. One patient had IgM antiphospholipid antibodies before placement, and 1 additional patient became positive after placement. In patients with a preexisting antibody, increased titers and additional specificities developed subsequent to placement.

CONCLUSIONS

All but 1 patient showed development of phospholipid-binding plasma protein-dependent antiphospholipid antibodies after left ventricular assist system placement.

Pathogenetic factors underlying juvenile deep vein thrombosis (DVT) in Indians

The role of hereditary antithrombotic protein defects in juvenile deep vein thrombosis (DVT) was evaluated. Fifty six young patients (age <45 yr) with doppler-proven DVT were investigated for the presence of resistance to activated protein C (APC-R), lupus anticoagulant (LA), anticardiolipin antibodies and deficiencies of protein C, protein S, ATIII activities. Fifty nine normal healthy individuals served as controls. APC-R was observed to be the commonest defect underlying the Indian DVT as seen in 39.2% of patients followed by elevated ACA (5.3%), PAI (2.8%), presence of LA (2.8%) and reduced ATIII levels (2.8%). None of the subjects had protein C or S deficiency. APC-R was associated with ATIII deficiency in one case, and elevated ACA in two cases. In two subjects, APC-R was associated with elevated PAI levels. Patients with more than one prothrombotic factor had a higher prevalence of pulmonary thromboembolism, suggesting that the thrombogenic potential of APC-R is enhanced by the presence of coexisting hereditary or acquired prothrombotic defect.

The use of frozen-thawed platelet-derived phospholipids as a confirmatory test for the diagnosis of lupus anticoagulants. Comparison with two commercial confirmatory system tests

Lupus anticoagulants (LAs) belong to acquired circulating anticoagulants interfering with phospholipid-dependent coagulation tests. Owing to the remarkable variability among patients, SSC guidelines recommend more than one test to detect and confirm the presence of LAs. However, this is an expensive procedure and greatly raises the work load of the laboratory. A standardised platelet-derived phospholipid preparation was obtained and platelet neutralisation (PNP) procedures with APTT and DRVVT reagents were performed on plasmas from 16 patients with LAs and from 41 control subjects. In comparisons, STAclot-PNP and DVVconfirm clotting assays were conducted. PNP by using APTT or DRVVT reagents showed intra-assay coefficient of variation of 1.6 and 1.8%, whereas inter-assays coefficient of variations were 6.8 and 5.1%, respectively. A complete concordance was achieved between STAclot-PNP and PNP by using APTT reagents and between DVV-confirm and PNP with DRVVT reagents, demonstrating a high reliability of both the PNP-based assays. This consistency indicates that the standardised platelet-derived phospholipid preparation obtained allows for reliable, reproducible, and cheap PNP-based confirmatory assays for LAs testing.

Do antiphospholipid antibodies interfere with tissue factor pathway inhibitor?

This study was conducted to investigate whether antiphospholipid antibodies (APA) can interfere with the phospholipid-dependent inhibition of coagulation exerted by tissue factor pathway inhibitor (TFPI). Eleven patients with APA and eleven healthy controls matched for age and gender were enrolled. Blood samples were drawn before and 5 minutes after an intravenous injection of unfractionated heparin 5000 IE, which is known to cause TFPI release in healthy individuals. The preheparin samples showed significantly higher TFPI free antigen levels in the APA positive patients than in the controls (21.7 vs. 14.2 ng/ml, p = 0.03). TFPI activity as measured in a chromogenic substrate assay also was higher in patients, but this difference was not statistically significant (1.13 vs. 1.01 U/ml, p = 0.2). The TFPI levels showed a considerable rise in both patients and controls after heparin injection. In both assays, the postheparin levels were significantly higher in patients than in controls (TFPI antigen: 179 vs. 153 ng/ml, p = 0.05; TFPI activity: 3.26 vs. 2.51 U/ml, p = 0.03). A modified diluted prothrombin time assay (dPT) was used to measure TFPI anticoagulant activity. In this assay, samples from the patients with the strongest effect of lupus anticoagulants (LAs) on preheparin coagulation times showed little or no increase after heparin injection. This result may reflect an inhibition of TFPI anticoagulant activity by strong LAs. In conclusion, we have found that patients with APA have higher TFPI amidolytic activity/antigen level both before and after heparin stimulation of TFPI release. These observations do not explain the higher thrombotic risk in these patients but may reflect an upregulated tissue factor activity, which has been demonstrated in these patients. TFPI anticoagulant activity, however, as measured in a dPT assay, may be inhibited by strong LAs.

Deep-vein thrombosis

Deep-vein thrombosis is an important complication of several inherited and acquired disorders, but may also occur spontaneously. Prevention of recurrent venous thrombosis and pulmonary embolism is the main reason for accurate diagnosis and adequate treatment. This seminar discusses only symptomatic deep-vein thrombosis. The diagnosis can be confirmed by objective tests in only about 30% of patients with symptoms. Venous thromboembolic complications happen in less than 1% of untreated patients in whom the presence of venous thrombosis is rejected on the basis of serial ultrasonography or ultrasonography plus either D-dimer or clinical score. Initial anticoagulant treatment (intravenous or subcutaneous heparin) should continue until oral anticoagulant treatment, started concurrently, increases the international normalised ratio above 2.0 for more than 24 h. The optimum duration of oral anticoagulant treatment is unresolved, but may be guided by the presence of temporary or persistent risk factors or presentation with recurrent venous thromboembolism.

Clinical significance of lupus anticoagulants in children

OBJECTIVES

To determine the spectrum of associated clinical manifestations and time course of lupus anticoagulants (LA) in children.

STUDY DESIGN

Retrospective study of 95 consecutive children (46 boys and 47 girls), with a median age of 5.3 years (range, 1.7 to 17.1 years), diagnosed with presence of LA at a hemostasis referral center; 83 were followed up over a median of 2.9 years (range, 6 weeks to 21.6 years).

RESULTS

At diagnosis, 80 of 95 (84%) children were free of symptoms, and presence of LA was found incidentally. Nine children (10%) had bleeding symptoms, 5 (5%) had thrombotic events, and 1 had systemic lupus erythematosus. Among the patients with bleeding, 5 had transient severe hypoprothrombinemia after adenovirus infections, and 3 had thrombocytopenia. None of the children who were initially free of symptoms had bleeding, thrombotic complications, or autoimmune disease subsequently. At follow-up, 48 of 83 (58%) patients had normal activated partial thromboplastin time values after 1.9 years (5 weeks to 19.1 years). Thirty-two (38%) still had activated partial thromboplastin time elevations but did not fulfill all criteria for presence of LA after 3.2 years (7.4 months to 9.3 years). Three (4%) patients, who had presented with thrombosis, had persistent positive LA, anti-cardiolipin, and antinuclear antibodies after 1.4, 2.8, and 7.5 years, respectively. One of these had recurrent thrombosis.

CONCLUSIONS

In most children the presence of LA did not lead to clinical complications and was transient. Bleeding occurred with additional hypoprothrombinemia or thrombocytopenia. Thrombosis was rare and strongly associated with persistently positive LA.

The interdisciplinary team's approach to lupus nephritis

The interdisciplinary team approach in assessment and treatment of patients with chronic disease in general and lupus nephritis in particular provides a global format for identifying the multiple problem areas that retard or prevent optimal patient functioning. These areas include the physical, emotional, economic, psychosocial, and functional. Benefits to the individual patient include a thorough multifaceted assessment by professionals who have the benefit of peer collaboration and validation. This increases the likelihood that the whole patient is considered, not just the problem of nephritis. For example, how does the patient and her or his family cope with the impact of such a disease and how, in turn, do the coping abilities of the patient and family affect the disease. The interdisciplinary team also assesses how the treatment strategies for each problem area influence each other. Finally, the interdisciplinary team serves as a positive role model for effective collaboration among health professionals and for students in their respective disciplines.