[Antiphospholipid antibodies: clinical significance and biological diagnosis]

The term "antiphospholipids" (aPLs) refers to an heterogeneous family of antibodies diagnosed either by clotting tests: the lupus anticoagulants or by Elisa: anticardiolipin (aCL) and anti-beta2-glycoprotein I (anti-beta2GP1) especially. aPLS recognize phospholipids, alone or bound to plasma protein cofactor(s), or the cofactors themselves. aPLs have long been described in autoimmune diseases such as SLE, but may also be found in other clinical settings including infections, malignancies and drug administration. Their persistent presence can be associated with venous and/or arterial thrombotic complications and/or recurrent miscarriage, thus defining the "antiphospholipid syndrome" (APS). The heterogeneity of aPLs makes a comprehensive approach to laboratory investigation essential. Detection of lupus anticoagulants relies on increased clotting times in phospholipid-dependent tests. Their 4 step diagnosis includes: 1) screening (by at least two different tests); 2) demonstration of an inhibitory activity; 3) evidence of its phospholipid dependence; 4) exclusion of an associated coagulopathy. Among the aPLs detected by Elisa, IgG aCL are the most frequently investigated. However, other antibodies may represent useful biological tools. Among them, anti-beta2GP1 are thought to be more closely associated with a history of thrombosis than aCL and testing for anti-beta2 GP1 should now be systematically included in the biological diagnosis of APS. The Elisa used for aCL and anti-beta2GP1 are not fully standardized, and a number of methodological parameters may account for the interlaboratory discrepancies often observed. The clinical importance of other antibodies such as antiphosphatidylethanolamine, antiprothrombin or antiannexin V is being evaluated. An appropriate laboratory investigation of APS should, in all cases, combine the use of clotting and immunological assays, and assess the persistence of autoantibodies over time.

Reduced factor XII levels in patients with the antiphospholipid syndrome are associated with antibodies to factor XII

Antibodies to factor XII (FXII) have previously been identified in some patients who were lupus anti-coagulant-positive. The relationship between these antibodies and FXII levels appeared to be variable. The aim of the present study was to confirm the presence of antibodies to FXII in patients with well characterized antiphospholipid syndrome (APS) and to establish their potential effect on levels of FXII. Forty-two patients with APS were studied; 21 patients were found to have either immunoglobulin (Ig)G or IgM antibodies to FXII by enzyme-linked immunosorbent assay (ELISA) using a highly purified preparation of FXII (> 99% pure). Levels of FXII were statistically significantly lower (P = 0.02) in patients with antibodies to FXII when compared with patients without antibodies to FXII (median = 91 micro/dl, s.d. = 39.1, median = 122 micro/dl, s.d. = 41.1 respectively). Four of the 21 patients with antibodies to FXII were found to have FXII levels below the laboratory normal range. Antibodies to FXII are present in significant numbers of patients with APS and may lead to acquired FXII deficiency.

"Pauci-Immune" proliferative and necrotizing glomerulonephritis with thrombotic microangiopathy in patients with systemic lupus erythematosus and lupus-like syndrome

In the glomerulonephritides of systemic lupus erythematosus (SLE), the number of subendothelial deposits, when present, generally corresponds to the degree of light microscopic glomerular hypercellularity; only very rarely are no or few such deposits present in cases of focal (WHO class III) or diffuse (WHO class IV) proliferative lupus nephritis. We have recently encountered five cases of active diffuse proliferative glomerlonephritis with no subendothelial and few or no mesangial deposits and thrombotic microangiopathy (TMA) in four patients with SLE and one patient with lupus-like syndrome. Three of the five patients were tested for circulating lupus anticoagulants or anticardiolipin antibodies, and two were positive. All five patients tested negatively for antineutrophil cytoplasmic antibodies (ANCA). Three patients responded to steroid and cyclophosphamide treatment, although one of them died of acute bacterial bronchopneumonia. One patient was lost to follow-up. We conclude that "pauci-immune" proliferative lupus nephritis is rare and should be treated as proliferative lupus nephritis with a proportionate number of subendothelial deposits. The negative ANCA suggests that these cases do not represent incidental ANCA-associated pauci-immune necrotizing and crescentic glomerulonephritis in patients with SLE. Of particular interest is that, in patients with SLE, if associated with TMA, an active proliferative necrotizing glomerulonephritis may be present even in the absence of significant glomerular immune complex deposition.

Bilateral non-arteritic anterior ischemic optic neuropathy in a patient with autoimmune thrombocytopenia

PURPOSE

To describe a patient with bilateral non-arteritic anterior ischemic optic neuropathy (NAION) and idiopathic autoimmune thrombocytopenia (ITP) with an extremely low platelet count.

METHOD

Case report.

RESULTS

Remarkably good recovery of visual acuity.

CONCLUSIONS

Bilateral non-arteritic anterior ischemic optic neuropathy can develop in the presence of a very low platelet count.

A reversible bilateral renal artery stenosis in association with antiphospholipid syndrome

We describe a 26-year-old white female with a history of Raynaud phenomenon, erythema nodosum, polyarthralgias, migraine, vertigo, seizures, transient ischemic attacks, one fetal loss, and false positive VDRL, who developed milk hypertension without overt lupus nephritis. She had positive antinuclear antibodies (ANA) and double-stranded deoxyribonucleic acid (dsDNA) antibodies. The lupus anticoagulant test (LAC) and cardiolipins antibodies (aCL) were positive. She was diagnosed as having a Systemic Lupus Erythematosus-like illness (SLE-like) with 'secondary' antiphospholipid syndrome (APS). Renal spiral computed tomography (CT) with intravenous (IV) contrast showed bilateral renal artery stenosis. Anticoagulation with acenocumarol was started. She became normotensive without antihypertensive drugs five months later. A follow-up renal spiral CT showed complete recanalization of both renal arteries, making thrombosis the more likely culprit pathology in the stenosis. After two years follow up the patient is normotensive. She remains on acenocumarol.

[Constitutional thrombophilias: indications of the biological profile and therapeutic consequences]

In laboratory screening in patients with clinical thrombophilia (early thromboembolism episode < 50 years, spontaneous thrombosis, recurrent thrombosis, unusual site of thrombosis, thrombotic family history or coumarin-induced skin necrosis complication), an isolated or combined inherited thrombophilia can be observed: antithrombin (0.5 to 4.9 per cent), protein C (1.4 to 8.6 per cent) and protein S (1.4 to 7.5 per cent) deficiencies or factor V Leiden (20 to 30 per cent). Special attention is mandatory in prescribing biological exploration because of the many physiological or pharmacological interferences which can modify the results. Identification of a genetic defect may induce specific management and individuals should receive counselling regarding the implications of this diagnosis. Further prospective studies should help to determine the thrombotic risk in symptomatic and non-symptomatic patients with inherited thrombophilia and the risk/benefit ratio of laboratory screening for hereditary thrombophilia and therapeutic intervention.

Thyroid autoimmunity and its association with non-organ-specific antibodies and subclinical alterations of thyroid function in women with a history of pregnancy loss or preeclampsia

Following the observation that non-organ-specific antibodies are related with pregnancy loss and preeclampsia, the role of organ-specific antibodies is currently being extensively investigated. The aim of this study was on the one hand to evaluate the incidence of antithyroid antibodies in a study group of 69 women with a history of early pregnancy loss (subgroup 1), foetal death (subgroup 2) or preeclampsia (subgroup 3) and in a control group, on the other hand to assess the possible association of these autoantibodies with non-organ-specific antibodies and subclinical alterations of thyroid function in the study group. Antithyroid antibodies were present in 26/69 (37.7%) women of the study group (37.9% in subgroup 1; 40.9% in subgroup 2; 33.3% in subgroup 3) and in 10/69 (14.5%) of controls, the difference being statistically significant. A significant difference in the distribution of antibodies to thyroglobulin and thyroid peroxidase was found in subgroup 2. In the study group, the incidence of antiphospholipid antibodies was not significantly different in women positive (26.9%) and negative (34.9%) for antithyroid antibodies. Also, the overall incidence of subclinical alterations of thyroid function in the study group was significantly different in women positive (53.8%) and negative (16.2%) for thyroid autoimmunity (P<0.02). The results of this study seem to confirm the association between thyroid autoimmunity and obstetric complications and suggest the usefulness of undertaking prospective studies in order to evaluate the reproductive outcome of women with a history of recurrent abortion, foetal death or preeclampsia and positivity for antithyroid antibodies.

Thrombotic risk factors in pulmonary hypertension

Thrombotic lesions are consistently observed in chronic thromboembolic pulmonary hypertension (CTEPH) and frequently found in primary pulmonary hypertension (PPH). It remains unknown, however, whether thrombosis is related to defects of the antithrombotic pathway or to previous vascular injury. This study therefore analysed the frequency of both hereditary and acquired thrombotic risk factors in CTEPH and PPH. One hundred and forty-seven consecutive patients with CTEPH investigated in the author's institution were compared to 99 consecutive patients with PPH. In 116 CTEPH patients and 83 PPH patients, phospholipid-dependent antibodies (antiphospholipid antibodies and lupus anticoagulant) were analysed by both immunological and clotting assays. In patients enrolled since 1994 (46 CTEPH and 64 PPH), hereditary thrombotic risk factors were also determined. Antithrombin, protein C and protein S activities were measured by functional assays. Mutations of factor V and factor II were identified by polymerase chain reaction. The prevalence of hereditary thrombotic risk factors was not increased in patients with either PPH or CTEPH. In contrast, a high frequency of phospholipid-dependent antibodies was observed in PPH (10%) and more notably in CTEPH (20%). Moreover, in PPH, antibodies were present only in low titre whereas in CTEPH, half of the patients with antiphospholipid antibodies had high titres. In addition, in CTEPH all but one of the patients with lupus anticoagulant also had antiphospholipid antibodies. The most striking finding of this study was the high prevalence of phospholipid-dependent antibodies but their clinical relevance appears to be different in primary pulmonary hypertension and chronic thromboembolic pulmonary hypertension. In primary pulmonary hypertension, these antibodies in low titre probably reflect endothelial dysfunction. In contrast, in chronic thromboembolic pulmonary hypertension the presence of antibodies in high titre associated with lupus anticoagulant, underlines the role of thrombosis in the pathogenesis of this condition.

The role of beta 2-glycoprotein I-dependent lupus anticoagulants in the pathogenesis of the antiphospholipid syndrome

The antiphospholipid syndrome (APS) is defined as the association of antiphospholipid antibodies (aPL) with arterial or venous thrombosis, recurrent fetal loss, thrombocytopenia or neurologic disorders. Some aPL can be detected via phospholipid dependent coagulation assays where they present as an aspecific coagulation inhibitor termed the lupus anticoagulant (LA). Other antibodies can be measured via immunological assays mostly via their capability to bind to immobilised cardiolipin and are therefore called anticardiolipin antibodies (aCL). Affinity purification of aCL led to the discovery that, in contrast to what the term antiphospholipid antibody could suggest, these autoimmune antibodies do not bind to negatively charged phospholipids per se but to beta-2-glycoprotein I (beta 2GPI), a phospholipid-binding protein eventually bound to phospholipid surfaces. LAs have been found to be directed towards either prothrombin or beta 2GPI bound to anionic phospholipids. Whereas clinical and animal experimental data clearly suggest a role for beta 2GPI-dependent aPL in the development of the APS, the pathogenic mechanism is not known. Interferences with several phospholipid dependent anticoagulant pathways have been proposed but none of these has received general acceptance. Based on clinical and experimental similarities with heparin-induced thrombocytopenia, another syndrome of antibody mediated thrombosis, we proposed a model of prothrombotic cellular activation. This model, although supported by a number of experimental observations, does not provide a direct explanation for the recent observation that LA are more strongly associated with thrombosis than aCL. In order to study this, we raised murine monoclonal antibodies (moab) against human beta 2GPI. These antibodies, of which some had LA activities and others not, enabled us to study the interaction between beta 2GPI, antibody and phospholipids. In contrast to what was generally accepted, beta 2GPI appeared to have only low affinity for coagulation promoting phospholipids. In the presence of LA positive anti-beta 2GPI moabs, the affinity of beta 2GPI for phospholipids increased significantly. This appeared to be dependent on the formation of bivalent beta 2GPI-antibody complexes on the phospholipid surface. It is conceivable that such bivalent complexes also remain tightly attached to membranes of activated cells enabling further thrombosis promoting activation via Fc receptor interaction or the complement system, a hypothesis that is currently being investigated. Further studies also showed that our LA positive anti-beta 2GPI moabs have a potential for the production of LA control specimens, that could be made available to routine hemostasis laboratories to assess intra-laboratory precision of LA testing, to manufacturers to produce highly sensitive assay systems and to control batch-to-batch variability of their reagents and to organizations involved in external quality assessment. In conclusion this work has enabled us to understand the molecular mechanism by which certain autoimmune antibodies found in patients with APS prolong coagulation assays in vitro. The antibodies generated are an important tool to improve the laboratory diagnosis of the lupus anticoagulant and may help us clarify the pathogenic role of autoimmune anti-beta 2GPI antibodies.

[Lupus anticoagulant: complete automation (ACL-Futura) and diagnostic algorithm]

PURPOSE

The technical and clinical evaluation of a new laboratory profile with six tests, for the realization of the assay called "lupic anticoagulant" with the help of ACL-Futura analyzer (Intrumentation Laboratory).

RESULTS

The within-between day imprecision of the tests that compose the profile: APTT-Diluted, APTT-D Mix, LacScreen, LacScreen Mix, LacConfirm and LacConfirm Mix, are between 2.87%-11.61% with controls, this imprecision is lowest with patients. A study of bilirrubin and lipemia interferences is presented. The practicability study present the technical, time consuming difficulty, and shows that the cost of the screening test is about 1136 ptas (6.83 euros) and with the confirmative test is 2766 ptas (16.62 euros). The clinical study describes our preliminary results with the application of this new profile for almost 2 years and six clinical cases are presented.

CONCLUSIONS

The good technical and clinical results of the evaluation of the new profile proposed to detect the positive lupic anticoagulant, in addition to the fully automated assay with the ACL-Futura analyzer, validate the whole method to resolve the increased demand of these parameters.

A case of primary antiphospholipid antibody syndrome with acute renal failure showing thrombotic microangiopathy

An 18-year-old woman complained of fever and edema and was admitted to Showa University Hospital for treatment of thrombocytopenia and deteriorating renal function. Laboratory studies demonstrated the presence of lupus anticoagulant (LA), prolongation of prothrombin time, hemolytic anemia, a negative Coombs' test, the absence of antinuclear antibodies, and a normal fibrinogen level. Renal biopsy revealed mesangial hypercellularity, severe endocapillary cell damage, and double contour of the basement membrane walls. Immunofluorescence studies demonstrated focal, peripheral, and finely granular deposits for IgG, IgM, and IgA but were negative for fibrinogen. Electron microscopy showed glomerular capillary loops with subendothelial widening and subendothelial deposits, mesangiolysis, mesangial interposition, and marked luminal narrowing. Biopsy findings were consistent with thrombotic microangiopathy. The patient was treated with hemodialysis, methylprednisolone pulse therapy, and dipyridamole. After treatment, LA disappeared, the prothrombin time became normal, and renal function improved. The renal lesions in this patient were caused by primary antiphospholipid antibody syndrome. This case strongly suggests an important causal relationship between LA and renal lesions in thrombotic microangiopathy. We present this case to promote understanding of the pathogenesis of primary antiphospholipid antibody syndrome.

Spontaneous venous thrombosis in a young patient with combined factor V Leiden and lupus anticoagulant

We describe a case of a 28-year-old man who developed an extensive spontaneous deep venous thrombosis. Testing revealed heterozygotic factor V Leiden mutation, and the presence of both lupus anticoagulant (LA) and elevated IgM anticardiolipin antibody (ACA). Several family members were found to be heterozygous for factor V Leiden. A paternal aunt had the factor V Leiden mutation, an elevated plasma homocysteine and a borderline increased IgG ACA level. No other family member had a history of a venous thrombotic event. This case illustrates that evaluation of young patients who present with venous thrombosis should be performed for both hereditary and acquired thrombophilic defects. The family studies suggest that the presence of a lupus anticoagulant may be more clinically significant than elevated ACA in risk assessment. Although screening family members when the proband carries factor V Leiden is controversial, psychological reassurance of those who test negative and simple advice on occupations or social habits (e.g., smoking) for those who test positive may be important benefits.

Isolation and characterization of two human monoclonal anti-phospholipid IgG from patients with autoimmune disease

The antigenic specificity of anti-phospholipid antibodies (APA) is a matter of intensive investigation. To further characterize these antibodies, we attempted to isolate human monoclonal APA. B-cells of patients with at least one positive test for antibodies against cardiolipin, phosphatidylserine, beta2-glycoprotein I (beta2-GPI) or the lupus anti-coagulant were immortalized by transformation with Epstein-Barr virus and screened for production of specific IgG. Positive pools were fused with a heteromyeloma cell line and APA-secreting clones were isolated by standard procedures. Two monoclonal APA, HL-5B from a 51-year-old man with primary anti-phospholipid syndrome and recurrent cerebral microinfarctions, and RR-7F from a 48-year-old women with systemic lupus erythematosus but no evidence for thrombotic events were obtained. HL-5B is of the IgG2 subtype with lambda light chains, while RR-7F is IgG2 with kappa light chains. Both monoclonals show reactivity against cardiolipin and phosphatidylserine but lack reactivity against beta2-GPI or lupus anti-coagulant activity. To yield the same OD in the cardiolipin and phosphatidylserine ELISAs RR-7F must be used in an approximately 10-fold higher concentration than HL-5B, indicating a lower affinity towards these antigens. Interestingly, both mAPA can bind to cardiolipin in the absence of beta2-GPI. They do not cross-react with dsDNA but show reactivity against oxidized low-density lipoproteins. Analysis of the heavy chain mRNA of HL-5B and RR-7F showed that both are members of the VH3 family. While HL-5B shows extensive somatic mutations in the CDR1 and 2 regions, indicating that it was derived by a T cell-dependent antigen driven process, RR-7F is apparently germline encoded. The two monoclonal APA can be used as tools in further structural and functional analyses.

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.

Retinal vascular occlusion and deficiencies in the protein C pathway

PURPOSE

To report abnormalities in the protein C pathway and other vascular occlusion risk factors in patients with retinal vascular occlusion.

METHODS

In a study, we investigated 76 consecutive patients who had in-patient evaluation of venous or arterial retinal vascular occlusion. All patients underwent comprehensive tests for coagulation disorders including determinations of protein C, protein S, lupus anticoagulants, and resistance to activated protein C and were screened for vascular disease risk factors. Resistance to activated protein C was confirmed by a polymerase chain reaction method to detect the specific factor V R506Q mutation. For comparative purposes, we also screened 209 consecutive inpatients with deep vein thrombosis from the same geographic region for resistance to activated protein C as well as protein C and protein S deficiencies.

RESULTS

Ten (29%) of 35 patients with central retinal vein occlusion (CRVO) had factor V R506Q mutation. The factor V R506Q mutation was detected in four (19%) of 21 patients with branch retinal vein occlusion. The higher frequency in factor V R506Q mutation compared with the expected 9% mutation prevalence in a white population was highly significant for the central retinal vein occlusion group but not for the branch retinal vein occlusion group. In all patients with resistance to activated protein C, the factor V R506Q mutation was detected; 16 were heterozygous, one homozygous. No cases of lupus anticoagulants, protein C, or protein S deficiencies were detected. Forty (19%) of 209 patients with deep vein thrombosis were carriers of the factor V R506Q mutation.

CONCLUSIONS

The prevalence of the factor V R506Q mutation is similar in patients with central retinal vein occlusion and patients with deep vein thrombosis and represents a relevant risk factor. Screening for this mutation is therefore recommended in all patients with central retinal vein occlusion.

Polymorphism of beta2-glycoprotein I at codons 306 and 316 in patients with systemic lupus erythematosus and antiphospholipid syndrome

OBJECTIVE

To determine the frequency of mutations in the phospholipid binding domain of beta2-glycoprotein I (beta2GPI) in patients with systemic lupus erythematosus (SLE) and/or antiphospholipid syndrome (APS), and to analyze the clinical correlations of such mutations with thromboembolic complications.

METHODS

Exons 7 and 8 of beta2GPI, which encode for its fifth domain, were amplified by polymerase chain reaction, and the presence of mutations was determined by restriction digestion and single-strand conformation polymorphism analysis. A clinical correlation with these mutations and the presence of antiphospholipid antibodies (aPL), lupus anticoagulant (LAC), anti-beta2GPI antibody, and the development of thromboembolic complications was performed using chi-square and Fisher's exact tests.

RESULTS

From a total of 143 patients studied, we found that 5.6% were heterozygous for the mutation at exon 7 (codon 306), and 7.7% were heterozygous for the mutation at exon 8 (codon 316). No homozygous subjects were found for either mutation. No significant correlation between these mutations and the presence of aPL, LAC, or anti-beta2GPI antibodies was found. In patients with SLE (n = 95), 4 of 6 patients with exon 8 mutation had thrombosis, compared with 22 of 82 patients without the mutation (P = 0.043).

CONCLUSION

The prevalence of mutations in the fifth domain of beta2GPI in these patients with SLE and/or APS were similar to those previously reported for the general population. Heterozygosity for either mutation does not influence the incidence of aPL, but in patients with SLE, the mutation at exon 8 may predispose to thrombosis as an independent factor.

Immune abnormalities in endometriosis compromising fertility in IVF-ET patients

OBJECTIVE

To evaluate the incidence of immune abnormalities in patients with endometriosis and primary or secondary infertility.

STUDY DESIGN

This study analyzed the incidence of alloantibodies and autoantibodies in 100 women with endometriosis and 62 patients with unexplained infertility without endometriosis who enrolled in an assisted reproduction program at the Colombian Fertility and Sterility Center from January 1, 1996, to May 30, 1997. The alloimmune status of the women was determined by testing for the presence or absence of antileukocyte antibodies. The autoimmune studies included antinuclear antibodies, antiphospholipid antibodies and lupus anticoagulant antibody.

RESULTS

Negative titers of IgG antipaternal antibodies were identified in 34% of patients with primary infertility and in 34% of women with secondary infertility and a history of pregnancy losses. Positive titers of antinuclear antibodies were found in 27% (27/100) of the group of patients with endometriosis; of them, 30% (15/50) had primary infertility and 24% (12/50), secondary infertility. The average titer was 1/80. Forty-eight percent of the infertile patients (48/100) showed titers of antiphospholipid antibodies for IgG and IgM; 46% of these patients had primary infertility (23/50) and 50% (25/50), secondary infertility. This was significantly higher than in controls (P < .05). Two patients were positive for lupus anticoagulant antibody. In the group of patients with unexplained infertility without endometriosis, the incidence of antinuclear antibodies was 17.7% and of antiphospholipid antibodies, 30.6%.

CONCLUSION

For women with endometriosis, alloimmune and autoimmune evaluation is recommended prior to their undergoing assisted reproduction in order to provide appropriate therapy for each case.

The sensitivity and specificity of commercial reagents for the detection of lupus anticoagulant show marked differences in performance between photo-optical and mechanical coagulometers

This study was undertaken to appraise the application of those reagents most widely used in the UK for the detection and confirmation of lupus anticoagulant (LA) on an Amelung KC4A and a Sysmex CA-6000 coagulometer. Five sets of dilute Russell's viper venom time (DRVVT) reagents were assessed as well as the Textarin-PL/ Ecarin ratio. Each DRVVT method comprised both LA detection and confirmation reagents provided by the same manufacturer. Samples were obtained from 20 normal healthy subjects, 10 LA-positive patients, 10 patients receiving oral anticoagulant therapy (OAT) who had previously been documented as LA-positive, a further 10 LA-negative patients receiving OAT and 10 LA-negative patients receiving unfractionated heparin therapy. The sensitivity and specificity of the reagents exhibited considerable variation not only between reagents, but also when the same reagent was used on the two analysers. Sensitivity ranged from 62 to 97% (all reagents both analysers), specificity went as low as 23% (Gradipore reagent on the CA-6000) and as high as 100% (American Diagnostica Inc on both KC4A and CA-6000). On the KC4A instrument, Unicorn Diagnostics' lupus anticoagulant kit offered the best compromise of sensitivity and specificity (sensitivity 83% and specificity 81%). On the CA-6000 the reagents supplied by American Diagnostica Inc exhibited optimal performance (sensitivity 90% and specificity 100%). The results indicate a need to optimise test reagents for specific analyser types, a procedure which can only be undertaken with preparations such as the proposed NIBSC reference plasmas for the detection of lupus anticoagulant.

Association of antiphospholipid antibodies with retinal vascular disease in systemic lupus erythematosus

OBJECTIVES

To study the prevalence and characteristics of retinal vascular disease in patients with systemic lupus erythematosus (SLE) and to analyze their relationship with antiphospholipid antibodies (aPL) and other serological markers.

PATIENTS AND METHODS

Eighty-two consecutive patients (77 women and 5 men; mean age, 36 years) were studied. All patients fulfilled the 1982 revised criteria of the American College of Rheumatology for the classification of SLE. Ophthalmologic examination included assessment of best corrected visual acuity, tonometry, slit-lamp biomicroscopy, and fundus examination. Serologic studies included determination of anticardiolipin antibodies (aCL) (ELISA), lupus anticoagulant (LA) (coagulation tests), antinuclear antibodies (indirect immunofluorescence), anti-DNA (Farr's test), and anti-ENA antibodies (counterimmunoelectrophoresis).

RESULTS

Retinal vascular disease was detected in 13 (15%) of 82 SLE patients. The retinal lesions consisted of retinal vascular occlusions in six patients (five arterial and one venous), cotton-wool spots in three, optic disc edema in three, retinal hemorrhages in three, and ischemic optic neuropathy in one. Antiphospholipid antibodies were detected in 10 (77%) of these 13 patients: nine had aCL and two had the LA. When compared with patients without retinal vascular disease, patients with retinopathy had a higher prevalence of aPL (77% v. 29%, P = .005).

CONCLUSIONS

Retinal vascular disease is frequent in patients with SLE. The presence of aPL is associated with a higher prevalence of retinal abnormalities in SLE patients.

Myocardial infarction in patients with systemic lupus erythematosus with normal findings from coronary arteriography and without coronary vasculitis--case reports

The authors present the cases of two young patients, a man and a woman, who presented with myocardial infarction, in the absence of ischemic heart disease or stenosis of the coronary arteries. The woman was known to have systemic lupus erythematosus (SLE) for the past 3 years (the immunoglobulin M [IgM] anticardiolipins antibodies were positive), without a history of coronary risk factors. Suddenly she presented with acute chest pain on rest that lasted 4 hours and culminated in anterior wall myocardial infarction. She was admitted to the coronary care unit, where no thrombolysis was given. She did not have echocardiographic evidence of Libman-Sacks endocarditis, but myocardial infarction was evident at the electrocardiogram (ECG). The young man had SLE (the IgM anticardiolipins were absent, but he was positive for lupus anticoagulant antibodies), he was hyperlipidemic, was a moderate smoker and moderately obese, and had no history of ischemic heart disease. He suddenly presented with an acute myocardial infarction documented by ECG, enzymes, and gammagraphy. In both patients, coronary angiography findings were normal and myocardial biopsy did not show evidence of arteritis. The relevance of these cases is the rare association of ischemic heart disease in SLE, with normal coronary arteries and without evidence of arteritis or verrucous endocarditis.