Anticardiolipin Antibody Assay Research Articles

Challenges in laboratory testing of patients suspected of antiphospholipid syndrome: practical implications for clinicians.

This paper focuses on the laboratory tests necessary for the diagnosis of antiphospholipid syndrome (APS). Diagnosis starts with the selection of patients suspicious of having APS. The timing related to the clinical event is important to avoid false classification of APS patients. For the interpretation of the test results of antiphospholipid antibodies (aPL) understanding of all pitfalls and interferences is necessary. Lupus anticoagulant (LA) measurement remains a complex procedure with many pitfalls and interferences. The effect of anticoagulant therapy, the main confounder of LA measurement, can be overcome by removal agents for direct oral anticoagulants (DOAC) or by considering assays as Taipan snake venom time / Ecarin clotting time not affected by antivitamin K therapy and anti-Xa DOAC. However, both procedures have limitations. Solid-phase assays for anticardiolipin antibodies (aCL) and anti-β2-glycoprotein 1 antibodies (aβ2GPI) show inter-assay differences. Diagnosis is based on the measurement of three groups of aPL: LA, aCL and aβ2GPI, of IgG and IgM isotype. This allows to make antibody profiles that helps in identifying patients at risk. Other aPL, such as antibodies against the domain I of β2GPI and anti-phosphatidylserine-prothrombin antibodies may be useful in risk stratification of APS patients and in some specific situations of patients with incomplete antibody profile, but are not needed for diagnosis. Laboratory diagnosis of APS remains challenging. To increase the diagnostic efficacy and reliability, an integrated interpretation of all results and an interpretative comment should be provided on the laboratory report. Therefore, a close interaction between clinical pathologists and clinicians is mandatory.

Association of silent infarcts in sickle cell anemia with decreased annexin A5 resistance

BackgroundSickle cell anemia (SCA) is characterized by abnormally shaped, adhesive RBCs that interact with white blood cells and the endothelium, leading to chronic hemolysis, vasculopathy and a prothrombotic state. About 10% of subjects with a thrombotic event in the general population will have an associated antiphospholipid (aPL) antibody. One proposed mechanism for the thrombophilic nature of aPL antibodies is the disruption of the potent anticoagulant annexin A5 or Annexin A5 resistance (A5R). We designed a pilot study assessing the presence of aPL antibodies and disruption of A5R in pediatric sickle cell subjects. Methods39 subjects with SCA participated in this study. A5R, DRVVT, anti-β2GP1, anti-β2GP1, anti-phosphatidylserine and anti-cardiolipin antibody assays were performed. ResultsThere was a high prevalence of abnormal A5R despite a low prevalence of antiphospholipid antibodies. Multivariate logistic regression analyses showed an association with silent infarcts (p=0.015), lower hemoglobin (p=0.037), older age (p=0.047) and abnormal A5R. ConclusionWe report an association between annexin A5 resistance and presence of silent infarct, low hemoglobin, and older age in a subgroup of SCA subjects. A potential role for perturbed A5R in the pathophysiology of SCA needs to be evaluated further.

Risk factors for thromboembolism and pulmonary artery hypertension following splenectomy in children with hereditary spherocytosis

The aim was to study risk-factors for vascular thrombosis and incidence of pulmonary artery hypertension (PAH) in splenectomized children with hereditary spherocytosis (HS) at a single center. Pre- and post-splenectomy hemoglobin and platelet counts were recorded. Post-splenectomy lipid-profile, fibrinogen, D-dimer, CRP and anti-coagulant-protein levels were compared to established controls. Echo-Doppler was performed for PAH. Twenty-six children with HS had undergone splenectomy; the mean age at surgery was 7.9 ± 3.7 years. Nineteen of the 26 were prospectively investigated at a median duration of 4.5 years (range: 4 months to 19 years) following splenectomy. Thrombocytosis was observed in 19 (73%), whereas no patient had erythrocytosis at the last follow-up visit. Total cholesterol, LDL-C, HDL-C, and triglyceride levels were not deranged (P ≥ 0.3). Mean CRP levels (males: 2.8 ± 0.5; females: 2.1 ± 0.5 mg/L) were significantly higher than described for normal children (P < 0.001). Six (23%) patients had a positive D-dimer assay. Protein S, anti-thrombin-III and fibrinogen were in range. A single patient had a borderline low protein C activity. Lupus anticoagulant and anti-cardiolipin antibody assays were negative. The mean tricuspid regurgitant jet velocity (TRJV) was 1.8 ± 0.55 meter per second (range: 0-2.4). None had a TRJV ≥2.5 meter per second to suggest PAH. There was no evidence of PAH, dyslipidemia, elevation of fibrinogen or a reduction in anti-coagulant proteins, at a median follow-up duration of 4.5 years following splenectomy in children with HS. However, elevated CRP level (42%), persistent thrombocytosis (73%) and elevated D-dimer levels (23%) were observed. These have been recognized as risk factors for cerebrovascular and coronary heart disease.

Development of Recombinant Human IgA for Anticardiolipin Antibodies Assay Standardization

Controls and calibrators in autoimmune assays are typically developed from patient sera. However, the use of sera is accompanied by a number of disadvantages, such as lack of monospecificity, lack of assay comparability, and supply limitations. Ideally, the control reagent would be an antigen-specific human monoclonal antibody preparation that is defined and pure, easy to produce without any supply limitations, and of defined isotype (IgG, IgM, or IgA). The generation of antigen-specific human monoclonal antibodies has been complicated, but recent advances in development of fully human antibodies by means of in vitro antibody gene library selection has opened a way for the isolation of human antibodies to virtually any antigen, including self-antigens. Such antibodies can be converted to any isotype by gene cloning. Here we developed a set of human monoclonal IgA antibodies specific for the cardiolipin-beta2-glycoprotein 1 complex, using the HuCAL technology. We evaluated the IgA variants of those antibodies for their use as standards in IgA anticardiolipin antibody assays and compared these reagents with serum controls. Such recombinant antibodies may ultimately replace patient sera as assay control and calibration reagents.

The utility of the Taipan snake venom assay in assessing lupus anticoagulant status in individuals receiving or not receiving an oral vitamin K antagonist

The objective of the present study was to evaluate the Taipan snake venom time (TSVT) assay in the detection of lupus anticoagulant in patients receiving or not receiving oral vitamin K antagonists. Blood samples were collected from individuals requiring investigation for the presence of a lupus anticoagulant. The TSVT test was run in parallel with the dilute Russell viper venom time (dRVVT) assay and anticardiolipin antibody assays. Results were assessed by Bayesian statistics. Two thousand and five plasma samples were obtained from 1335 individuals. One thousand, one hundred and eleven individuals were not receiving oral vitamin K antagonists; of these, 451 had a lupus anticoagulant by conventional testing, and the TSVT showed a sensitivity of 22%, specificity of 98%, positive predictive value of 80%, negative predictive value of 78%, positive likelihood ratio of 12.3 and a negative likelihood ratio of 0.790. Two hundred and ten of the 224 patients receiving oral vitamin K antagonists were known to have a persistent lupus anticoagulant prior to oral anticoagulation. In this setting, TSVT had a sensitivity of 39% and specificity of 93%, but the dRVVT had a 50% false-positive rate, which meant that despite having a higher sensitivity at 61% than the TSVT, its specificity was only 53%. TSVT is a specific but insensitive assay for the lupus anticoagulant in individuals not receiving oral vitamin K antagonists, when assessed against the dRVVT as the gold standard. It can be argued that despite the TSVT's poor sensitivity in patients taking oral vitamin K antagonists, its high specificity and positive predictive value make it a preferable assay to the dRVVT to diagnose lupus anticoagulant in this group.

Thrombophilic Patients with Migraines Have a High Incidence of Antiphospholipid Antibodies.

Migraines are associated with an increased risk of stroke and are recognized as a non-stroke neurologic complicaton in the antiphospholipid syndrome (aPls). Traditional tests for antiphospholipid antibodies (APA) include PTT assays [aPTT, dRVV, and Hexagonal phospholipid (Hex PL)], a dilute PT assay (Tissue Thromboplastin Inhibition) for lupus anticoagulants (LAC), and ELISA assays for anticardiolipin antibodies (ACA). These assays have not correlated with migraines. It is now recognized that antibodies to a phospholipid binding protein called beta-2-GPI are important in autoimmune aPls. Some patients (pts) with aPls are sero-negative, eg. negative in the routine assays, but have + anti-beta-2-GPI antibodies. Animal studies have shown an association of the latter antibodies to neurologic dysfunction. This study is a clinical retrospective medical record methodology, examining the relationship between migraines and APA results in pts referred to the Hemostasis & Thrombosis Clinic at the Institute for Transfusion Medicine from 7/1/03-7/15/05. Inclusion criteria were any pt. referred to the PI, who had a LAC screening panel and anti-beta-2-GPI testing. Exclusion criteria were any pt who did not have this testing or were + without repeat testing >2 mos later. Abstracted data included history of migraines (with or without aura), opthalmic migraines, referral reason, age, sex and APA results. Results were considered to be + (in non-anticoagulated pts), if any of the clotting assays were repeatedly +, did not correct on a mix, and shortened with phospholipid. Patients with only a + clotting assay, were taken off coumadin (OAC) and retested. Patients with + ELISA assays on OAC Rx, required an abnormal dRVV mix and/or a + Hex PL assay to be considered as + for a LAC. ELISA results were considered as +, if they were low titer or higher, e.g. ≥ mean ± 3 SD. The cohort consisted of 258 pts (69M: 189F) with a median age of 48 (range=13–85). Of these, 76 (29%) had migraines. Thirty-five/258 (13.6%) of the pts were referred for risk assessment and 10/35 (28.6%) had migraines. The remaining 223 pts were referred for clinical events: arterial or venous thrombosis [n= 133/233 (59.6%)], neurologic reasons [n=62/223 (28.2%)] and other [n=27/233 (12.1%)]. Of this group, migraines were present in 66 (29.6%). None of the 10 risk pts with migraines had + results. One of the 25 risk pts had a + anti-beta-2-GPI antibody (1/25=4.0%). Positive APA were detected in 58/233 (24.9%) pts with clinical events. Table 1 is a breakdown of the APA results vs migraines in pts with events vs those evaluated for risk issues. It appears that pts with thrombotic events with migraines have a higher incidence of +APA than those who do not have migraines. This data supports the suspected association between migraines and APA in the thrombphilic pt population. The same does not appear to be true in pts (without a thrombotic event) undergoing risk assessment.Incidence of Positive APA in Patients with regard to Migraine StatusGroupTotal PosTotal NegPORCIRisk-no migraine1/25 (4%)24/25 (96%)Risk-migraines0/10 (0%)10/10 (100%)1.000.8100.03–21.5Events-ALL pts58/233 (25%)175/233 (75%)0.00211.271.51 to 84.2Events-no migraine30/157 (19%)127/157 (81%)0.0585.830.77 to 44.22Events-migraines28/66 (42%)38/66 (58%)<0.00125.053.23 to 194.2APA = LAC/ACA and/or anti-beta-2-GPI

Is It Time To Reconfigure Lupus Anticoagulant Panels?.

Traditional lupus anticoagulant (LAC) panels are designed to test the presence/absence of antiphospholipid antibodies (APA). These usually include testing for a LAC with clot based assays (dRVV, Hex PL, aPTT) or with the tissue thromboplastin inhibition assay (TTI) and ELISA assays for anticardiolipin antibodies (ACA). It is now recognized that antibodies to a phospholipid binding protein, beta-2-GPI are important in the autoimmune form of the antiphospholipid syndrome (aPls). Moreover, some patients (pts.) may only be positive in this latter testing and have what is termed sero-negative aPls. The present study is a retrospective medical record review methodology to analyze the results of APA tests in 258 consecutive pts. referred to the PI at the Hemostasis & Thrombosis Clinic at the Institute For Transfusion Medicine. Inclusion criteria were any pt. who had a lupus panel and anti-beta-2-GPI (IgG, IgM and IgA) testing performed. Exclusion criteria were any pts. who did not have this testing or pts. with positive results which were not repeated > 2 months later. The cohort consisted of 258 pts (69M:189F) with a median age of 48 (range=13–85). Of these pts., 35 (13%) were referred for risk assessment, 133 (52%) for arterial or venous thrombosis, 62 (24%) for neurologic reasons, and 27 (11%) for other reasons. Patients on no anticoagulation (OAC) were considered to be LAC+, if any of the clot based assays was repeatedly positive, did not correct on a mix, and shortened with the additon of phospholipid. OAC pts. with positive ELISA assays were considered to have a LAC if the dRVV was positive on a mixing study and/or if the Hex PL test was positive. OAC pts. with only evidence for a LAC, were taken off OAC and then studied. ELISA assays were considered to be positive if low titer positive or higher, e.g. ≥ 3 STD above the mean. Positive results were found in 59/258 (22.8%) of these pts. The antibody results are listed in the table below in the pts. referred for risk assessment and in the pts. referred with events. The results are listed in categories of APA positivity.Antiphospholipid Antibody Results In Pts With Risk Assessment and Pts With Clinical EventsPt. GroupLAC+beta-2-GPILAC OnlyBeta-2-GPI OnlyACA OnlyTotalRisk Assessment0/35 (0%)0/35 (0%)1/35 (3%)0/35 (0%)1/35 (3%)Pts. With Events26/233 (11%)12/233 (5%)20/233 (9%)0/35 (0%)58/233 (25%)Total Positive Results26/59 (44%)12/59 (20%)21/59 (36%)059NOTE: 36% of the positive pts. would be missed by the traditional LAC panel.These results indicate that one-third of the pts. with phospholipid antibodies were sero-negative, e.g. negative in the presently constructed panels but positive for anti-beta-2-GPI antibodies. Skeptism exists about the meaning of isolated anti-beta-2GPI positivity. Of the pts. with only + beta-2-GPI antibodies, one male was asymptomatic (5%). The remaining pts. in this group were females. Ten/twenty-one (48%) of the pts. with isolated beta-2-GPI positivity were referred for neurologic reasons. These consisted of TIA's in 6, complex migraines with TIA's and acral cyanosis (1), recurrent fetal loss and TIA's in 3. Eight pts. (38%) had recurrent venous thromboembolism and 2 (9%) had both arterial and venous thromboembolism. We suggest that it may be time to consider constructing LAC screening panels containing tests for both LAC and anti-beta-2-GPI antibodies (all three isotypes) as sero-negative APls appear to be fairly common in females referred for thrombophilic testing.

A multi-centre evaluation of the intra-assay and inter-assay variation of commercial and in-house anti-cardiolipin antibody assays

To assess the intra-assay (intra-run) and inter-assay (inter-run) variation of commercial and in-house IgG and IgM anti-cardiolipin antibody (aCL) assays/kits, and to determine an appropriate maximum value for inclusion in consensus guidelines. Frozen aliquots of two patient specimens and one commercial control were sent to nine laboratories for the evaluation of eight commercial kits and one in-house assay. Intra-assay and inter-assay evaluations were performed with all three samples for IgG aCL, and one patient specimen for IgM aCL. The IgG and IgM aCL values varied considerably between the nine assays/kits. The majority of assays/kits demonstrated less than 20% intra-assay and inter-assay variation, with lower intra-assay and inter-assay variation observed with the commercial control. Single calibrator assays were not consistently associated with higher inter-assay variation than multi-point calibrator assays. An inter-assay coefficient of variation of 20% was determined to be an appropriate maximum value for inclusion in the Australasian aCL Working Party consensus guidelines. Improved standardisation between different assay/kits is still required.

Beta‐2‐glycoprotein I antibodies in patients with thrombosis

The laboratory diagnosis of antiphospholipid antibody syndrome currently requires two consecutive positive results in either lupus anticoagulant or anticardiolipin antibody assays. Antibodies against beta‐2‐glycoprotein I (aβ2‐GPI) are suggested as a new marker for the syndrome. The inclusion of aβ2‐GPI in the official diagnostic criteria has so far been precluded owing to lack of an international standard and also technical difficulties. Samples from 5367 consecutive patients sent to a national reference laboratory mainly because of various thrombotic events were studied. An IgG aβ2‐GPI ELISA assay was performed in addition to lupus anticoagulant (dRVVT and PTT‐LA) and IgG anticardiolipin antibody determinations to evaluate patient groups in which the new assay might be of value. From a total of 90 patients, 2.2% of the samples were aβ2‐GPI positive; 51 patients had aβ2‐GPI as the only positive antiphospholipid antibody marker; 20 patients had had a venous thrombosis and 14 an arterial thrombosis, 4 had pregnancy complications and 2 had thrombocytopenia. Relatively young patients with cerebrovascular ischaemic events seemed especially to present sole aβ2‐GPI positivity. The aβ2‐GPI positivity remained fairly constant in the 23 patients from whom follow‐up samples were taken. It is concluded that the IgG aβ2‐GPI assay seems to be a potentially important additional diagnostic tool for the antiphospholipid antibody syndrome.

Beta-2-glycoprotein I antibodies in patients with thrombosis

The laboratory diagnosis of antiphospholipid antibody syndrome currently requires two consecutive positive results in either lupus anticoagulant or anticardiolipin antibody assays. Antibodies against beta‐2‐glycoprotein I (aβ2‐GPI) are suggested as a new marker for the syndrome. The inclusion of aβ2‐GPI in the official diagnostic criteria has so far been precluded owing to lack of an international standard and also technical difficulties. Samples from 5367 consecutive patients sent to a national reference laboratory mainly because of various thrombotic events were studied. An IgG aβ2‐GPI ELISA assay was performed in addition to lupus anticoagulant (dRVVT and PTT‐LA) and IgG anticardiolipin antibody determinations to evaluate patient groups in which the new assay might be of value. From a total of 90 patients, 2.2% of the samples were aβ2‐GPI positive; 51 patients had aβ2‐GPI as the only positive antiphospholipid antibody marker; 20 patients had had a venous thrombosis and 14 an arterial thrombosis, 4 had pregnancy complications and 2 had thrombocytopenia. Relatively young patients with cerebrovascular ischaemic events seemed especially to present sole aβ2‐GPI positivity. The aβ2‐GPI positivity remained fairly constant in the 23 patients from whom follow‐up samples were taken. It is concluded that the IgG aβ2‐GPI assay seems to be a potentially important additional diagnostic tool for the antiphospholipid antibody syndrome.

Anticardiolipin Antibody Assay: a Methodological Analysis for a better Consensus in Routine Determinations

Despite the widely recognized practical importance of anticardiolipin (aCL) ELISA, the reliability of this test has been recently discussed. In order to investigate this area on European scale, we sent to 30 experienced centers a questionnaire focusing on the diagnostic procedures applied to patients with antiphospholipid syndrome (APS) and on the detailed protocols used to perform aCL. Anticardiolipin ELISA was found to be the most frequently performed test in patients with suspected APS, but significant difference was shown among the various protocols. The cross-laboratory multiple examination of ten serum samples evaluated independently by the 24 centers pointed out the difficulty in getting comparable results. Therefore a "consensus" protocol was derived from the aCL methods giving the best performance. The materials and reagents necessary to perform the "consensus" method, including, as putative standards, one IgG and one IgM monoclonal antibody (HCAL and EY2C9) were distributed to 19 Centers. The results of one IgG and one IgM aCL high positive sera measured in serial dilutions were compared. A progressive decrease in the variability of the values obtained for a given sample appeared evident when all the laboratories used the same standard, in their own in-house ELISA and even more in the "consensus" ELISA. Our data show that aCL ELISA standardization is necessary in order to obtain comparable results in different laboratories.

A rational basis for antiphospholipid antibody testing and selective immunotherapy in assisted reproduction: a rebuttal to the American Society for Reproductive Medicine Practice Committee opinion

A rational basis for antiphospholipid antibody testing and selective immunotherapy in assisted reproduction: a rebuttal to the American Society for Reproductive Medicine Practice Committee opinion

Catastrophic antiphospholipid syndrome

In its classic presentation, the antiphospholipid syndrome manifests a combination of venous or arterial thrombosis and fetal loss, accompanied by elevations of antibodies directed toward negatively charged phospholipids, as measured by anticardiolipin antibody assays and/or positive lupus anticoagulant tests. The manifestations often include a moderate thrombocytopenia and, less commonly, hemolysis. In contrast, a less frequently encountered subset of the antiphospholipid syndrome, termed the "catastrophic" antiphospholipid syndrome, affects mainly small vessels predominantly supplying organs. The thrombocytopenia is usually marked, and a Coombs positive microangiopathic-type anemia may accompany the condition. Features of disseminated intravascular coagulation may be evident in some patients. It is fatal in approximately 50% of cases reported. Treatment should include not only adequate anticoagulation with intravenous heparin but also full doses of intravenous corticosteroids, to offset the systemic inflammatory response syndrome that occurs as a result of the extensive tissue damage, and plasmapheresis, using fresh frozen plasma. Parenteral antibiotics should be administered early if infection is suspected.

Which are the Best Biological Markers of the Antiphospholipid Syndrome?

The diagnosis of antiphospholipid syndrome (APS) requires the presence of both clinical and biological features. Due to the heterogeneity of anti-phospholipid antibodies (aPL) the laboratory approach for their detection includes clotting-based tests for lupus anticoagulant (LA) as well as solidphase assays for anticardiolipin antibodies (aCL). In addition, as it has been shown that autoimmune aPL recognize epitopes on phospholipid (PL)-binding plasma proteins, assays detecting antibodies to β2-glycoprotein I (β2-GPI) or prothrombin have been developed. The association between venous or arterial thrombosis and recurrent fetal loss with the presence of conventional aPL (LA and/or aCL) has been confirmed by many studies. The LA and IgG aCL at moderate/high titre seem to exhibit the strongest association with clinical manifestations of the APS. Several reports indicate that LA is less sensitive but more specific than aCL for the APS. Assays against PLs other than CL as well as the use of mixtures of PLs have been proposed to improve the detection of APS-related aPL. Concerning antibodies to PL-binding proteins (detected in the absence of PLs), there is evidence that anti-β2-GPI are closely associated with thrombosis and other clinical features of the APS. Moreover, these antibodies may be more specific in the recognition of the APS and in some cases may be present in the absence of aPL detected by standard tests. Many issues are still under debate and are discussed in this review, such as the problems of standardization of anti-β2-GPI assays, detection of the IgA isotype of aCL and anti-β2-GPI, the coagulation profiles of LA in the recognition of the thrombotic risk and the association of particular markers with subsets of patients with APS.

Clinical utility of anticardiolipin antibody assays: high inter-laboratory variation and limited consensus by participants of external quality assurance programs signals a cautious approach

Antibodies that bind phospholipid (anti-phospholipid antibodies [APA]) are a focus of major interest to both clinical and laboratory personnel across a variety of disciplines because of the assortment of disorders with which they are reportedly associated. A solid phase assay using cardiolipin as the test phospholipid (anti-cardiolipin antibody assay [ACA]) has now become a laboratory standard for the detection of APA. In the current report, data from two separate external quality assurance programs (QAP) and collected over the past four years, have been evaluated to assess the utility of the ACA. Despite attempted standardizations, exceedingly high inter-laboratory variation and a general lack of test result consensus would signal the adoption of a cautious clinical approach towards laboratory findings. For example, for a total of 21 cross-laboratory tested serum samples (tested for both IgG and IgM for 41 quantitative estimations), inter-laboratory variation for both ACA-IgG and ACA-IgM was higher than 50% in 20 of 41 testing cases (48.8%). The situation with regard to testing consensus was equally concerning. Total consensus (i.e., 100% of participating laboratories agreed that a given serum sample gave an ACA result of either negative or positive) occurred in less than 20% of cases for ACA-IgG. More importantly, in about 50% of serum testing occasions there was no general consensus in returned laboratory data (i.e., more than 80% of labs could not agree on whether a serum sample tested was either ACA-positive or ACA-negative). Thus, despite attempted international standardizations, exceedingly high inter-laboratory variation and a general lack of test result consensus would argue that the assay has limited utility. We conclude that single point laboratory results must be used with considerable caution before accepting that ACA activity is present in patient serum or not. We agree with recommendations indicating that laboratory tests should be repeated at least once prior to making a clinical diagnosis of any APS-like disorder.

Lack of Association Between Antiphospholipid Antibodies and First-Trimester Spontaneous Abortion: Prospective Study of Pregnancies Detected Within 21 Days of Conception

Objective: To determine the role of antiphospholipid antibodies and anticardiolipin antibodies in first-trimester losses, addressing experimental pitfalls that preclude excluding the possibility that these antibodies reflect merely the selection bias of studying couples only after they have already experienced losses. Design: Given that retrospective studies cannot exclude the possibility that such antibodies arise as a result of the fetal death, blood samples were obtained either before pregnancy or very early in pregnancy. Sera were obtained within 21 days of conception. Setting: Multicenter university-based hospitals (National Institute of Child Health and Human Development collaborative study). Patient(s): Subjects for the current study were 93 women who later experienced pregnancy loss (48 diabetic; 45 nondiabetic), matched 2:1 with 190 controls (93 diabetic and 97 nondiabetic) who subsequently had normal live-born offspring. Intervention(s): Sera from these 283 women were analyzed for antiphospholipid antibodies by enzyme immunoassay. In 260 of the 283 women (87 with pregnancy losses; 173 with live-born infants), sera were also available to perform assays for anticardiolipin antibodies by enzyme immunoassay. Main Outcome Measure(s): Pregnancy losses. Result(s): No association was observed between pregnancy loss and the presence of antiphospholipid antibodies or anticardiolipin antibodies. Levels of antiphospholipid antibodies were 6–19 PL/mL in 62.4% of the pregnancies that ended in losses and ≥20 PL/mL in 5.4%; among pregnancies resulting in live-born infants, the percentages were 56.8% and 6.8%, respectively. Of the pregnancies that ended in a loss, 5.7% had anticardiolipin antibodies ≥16 GPL/mL, compared with 5.2% of those ending in a live birth. Conclusion(s): This prospective study suggests that anticardiolipin antibodies and antiphospholipid antibodies are not associated with an increased risk for first-trimester pregnancy loss.

Acquired free protein S deficiency is associated with antiphospholipid antibodies and increased thrombin generation in patients with systemic lupus erythematosus

In order to determine whether there is a relationship between acquired free protein S deficiency and increased thrombin generation, we performed a cross-sectional study of patients with systemic lupus erythematosus (SLE). Plasma samples were assayed for free protein S and were correlated to levels of prothrombin fragments (F1 + 2); an elevated level of F1 + 2 was used as a surrogate marker for a prothrombotic state. Assays for anticardiolipin antibodies (ACA) and lupus anticoagulant (LA) were performed on two separate blood samples taken at least 3 months apart in order to detect the presence of antiphospholipid antibodies. Of the 36 subjects, 9 had reduced free protein S levels compared to 0 of 21 controls (P = 0.01) and the mean free protein S level was significantly lower in the SLE population than in controls (0.30 +/- 0.08 U/mL versus 0.43 +/- 0.10 U/mL, P < 0.001). Of the 24 subjects with antiphospholipid antibodies, 9 had reduced free protein S levels, compared to 0 of 12 subjects without antiphospholipid antibodies (P = .01). The mean F1 + 2 level was significantly higher in study subjects with reduced free protein S levels than in those with normal free protein S levels (1.22 +/- 0.50 nmol/L versus 0.78 +/- 0.27 nmol/L, P = 0.05). This study confirms an association between antiphospholipid antibodies and reduced free protein S levels and demonstrates that patients with SLE and acquired free protein S deficiency generate more thrombin than patients with SLE and normal free protein S levels. Further studies are needed to determine whether the thrombotic diathesis associated with the presence of antiphospholipid antibodies is directly caused by the concomitant presence of acquired free protein S deficiency.

Effects of repeated freeze-thaw cycles on anticardiolipin antibody immunoreactivity.

The effect of repeated freeze-thaw cycles on anticardiolipin antibody levels was evaluated using an enzyme-linked immunosorbent assay. Normal human serum was spiked with known quantities of freeze-dried human polyclonal anticardiolipin antibody IgG and IgM (19 samples each) or IgA (11 samples). Each spiked sample was split into four identical aliquots; one aliquot was never frozen, and the remaining three were taken through successive freeze-thaw cycles. All aliquots from each sample were evaluated on the same day using the same plate and reagents. A significant decline in mean anticardiolipin IgG levels occurred between the aliquot which had never been frozen and the one which had been through three freeze-thaw cycles (Student's t-test, P = .04). Although mean IgM and IgA values declined as well, the differences were not significant. When individual samples were evaluated the decline appeared to occur most often between the second and third freeze-thaw cycle. Eight anticardiolipin IgG and three IgM-containing samples which had been positive initially became negative by the third freeze-thaw cycle. These data show that handling and storage of serum used to perform anticardiolipin antibody assays are important potential sources of assay variability.

Pregnancy in systemic lupus erythematosus: Contraception, fetal outcome and congenital heart block

Acta Obstetricia et Gynecologica ScandinavicaVolume 73, Issue 6 p. 517-518 Pregnancy in systemic lupus erythematosus: Contraception, fetal outcome and congenital heart block Heikki Julkunen, Corresponding Author Heikki Julkunen 1Fourth Department of Medicine and the First and Second Departments of Obstetrics and Gynecology, Helsinki University Central Hospital, Helsinki, FinlandFourth Department of Medicine Helsinki University Central Hospital Unioninkatu 38 SF-00170, Helsinki, FinlandSearch for more papers by this author Heikki Julkunen, Corresponding Author Heikki Julkunen 1Fourth Department of Medicine and the First and Second Departments of Obstetrics and Gynecology, Helsinki University Central Hospital, Helsinki, FinlandFourth Department of Medicine Helsinki University Central Hospital Unioninkatu 38 SF-00170, Helsinki, FinlandSearch for more papers by this author First published: July 1994 https://doi.org/10.3109/00016349409013445Citations: 7AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume73, Issue6July 1994Pages 517-518 RelatedInformation

DIAGNOSIS OF ANTIPHOSPHOLIPID ANTIBODIES

The antiphospholipid antibody syndrome consists of a presentation with venous thrombosis, arterial thrombosis (or vasculopathy), recurrent pregnancy loss, or thrombocytopenia, in the setting of high-titer anticardiolipin antibody or lupus anticoagulant. Characteristics of the lupus anticoagulant (an antibody detected by a functional assay) and anticardiolipin antibody are reviewed, in light of new information on the role of plasma proteins, especially B2-glycoprotein I. The advantages and disadvantages of screening and confirmatory assays for lupus anticoagulant are detailed, as well as modifications of the anticardiolipin antibody assay to improve sensitivity and specificity.