Antiphospholipid antibodies: specificity and mechanism of action

Circulating lupus-type anticoagulant is associated with an increased risk of arterial or venous thrombosis. The laboratory identification of lupus coagulant requires at least 2 different in vitro phospholipid-dependent coagulation techniques: immunological assessment based upon Elisa-type tests using pure phospholipids complements the coagulation procedure, but does not replace it. Circulating lupus anticoagulant is correlated with anti-phospholipid antibodies specific to phosphatidyl serine. Relationships between circulating lupus anticoagulant and anti-cardiolipin seem complex and are discussed. In fact, an entire family of anti-phospholipid antibodies exists, whose relationship with clinical manifestations remains to be determined. The effects of anti-phospholipid antibodies on human endothelial cells are described.     

Circulating coagulation inhibitors in the acquired immunodeficiency syndrome

Abnormal coagulation profiles were identified in ten patients with the acquired immunodeficiency syndrome (AIDS) associated with opportunistic infections and malignancies. Activated partial thromboplastin times were elevated in all patients; three of seven had elevated prothrombin times. All patients had lupus-type anticoagulants characterized by rapid prolongations of the partial thromboplastin time in mixing studies, prolonged dilute thromboplastin inhibition assays, and increased Russell viper venom clotting times. Ivy bleeding times were prolonged in three patients with defective platelet aggregation. The lupus anticoagulant was isolated from the sera of healthy heterosexual men and from patients with AIDS with and without the lupus anticoagulant, and in the presence and absence of opportunistic infections. Both polyclonal IgM and IgG lambda from plasma with lupus anticoagulant interfered with clotting studies and platelet aggregation. The inhibitors usually accompanied active opportunistic infections and tended to disappear with successful resolution of infection.     

A Sensitive Test Demonstrating Lupus Anticoagulant and its Behavioural Patterns

The kaolin clotting time of platelet poor plasma was used as a sensitive test for detecting the lupus anticoagulant in mixtures of normal and patients' plasmas. Platelets were found to decrease the anticoagulant effect of a typical lupus inhibitor. Thus, high sensitivity in this test system was achieved by ensuring low platelet concentrations and omitting platelet lipid substitute. In 17 patients with disseminated lupus erythematosus (DLE), 12 had detectable inhibitor by this method, more than would be detected with routine coagulation tests. Mixing patterns were of four distinct types, representing three different modes of anticoagulant behaviour. The pattern (type 3) of plasma mixtures giving longer kaolin clotting times than the individual components could be reproduced in vitro by adding trace amounts of crude thrombin or platelet fragments to a more typical lupus anticoagulant-containing plasma; formation of such a mixing pattern by the plasma of a patient with DLE may therefore indicate activation of the coagulation pathway. Six patients with idopathic thrombocytopenic purpura (ITP) had no detectable inhibitor indicating that anti-platelet antibodies behave differently from the lupus anticoagulant.     

Lupus anticoagulant--antiphospholipid antibodies and thrombophilia. Relation to protein C--protein S--thrombomodulin

In order to define the behavior of the lupus anticoagulant and/or antiphospholipid antibodies, we investigated the possible association with protein C, protein S and thrombomodulin. In 19 patients with established diagnosis of an autoimmune disease and coexisting lupus anticoagulant protein C (antigen and activity), protein S (total and free), anticardiolipin and antiphosphatidylserine antibodies were estimated. In one case the IgG globulin fraction containing the inhibitor was separated. The activation rate of pure protein C to its activated form using thrombin/thrombomodulin as activator was then measured in the presence or absence of lupus anticoagulant. No overall decrease of protein C or protein S was detected in patients' plasma. Nevertheless, the lupus anticoagulant had a specific effect on the protein C system, inhibiting the catalytic activity of thrombomodulin without causing a functional protein C deficiency. This specific effect upon thrombomodulin can be a main cause, but not necessarily the only one, for the thrombophilic tendency of patients with the lupus anticoagulant.     

Budd-Chiari syndrome in a patient with the lupus anticoagulant

Lupus anticoagulant is an immunoglobulin that interferes with prothrombin conversion to thrombin and is manifested biochemically by prolongation of the partial thromboplastin time. Paradoxically, bleeding is rare in association with this anticoagulant, and deep leg vein thromboses, pulmonary emboli, and cerebrovascular accidents have been described in patients with this clotting inhibitor. This report describes the first case of Budd-Chiari syndrome associated with the lupus anticoagulant. The patient presented with abdominal pain and massive ascites. The Budd-Chiari syndrome was confirmed by liver biopsy and venography. No medical condition known to predispose to an increased thrombotic tendency could be identified, and the presence of the lupus anticoagulant in the patient's plasma may provide an explanation for his hypercoagulability and development of the Budd-Chiari syndrome.     

Performance of Platelin LS and dilute Russell's viper venom for the screening of lupus anticoagulant in patients with venous thromboembolism.

Lupus anticoagulant is associated with thrombosis and pregnancy morbidity, and its detection is of major clinical importance. The nature and concentration of phospholipids strongly influence the sensitivity of activated partial thromboplastin time (aPTT) reagents to lupus anticoagulant. We investigated the ability of Platelin LS, an aPTT reagent, to screen lupus anticoagulant among 94 patients with venous thromboembolism by comparing its performance with the dilute Russell viper venom time (dRVVT). Twenty-four patients had an abnormal aPTT and dRVVT, whereas 37 only had a prolonged dRVVT. In users of oral anticoagulants (n = 56), the dRVVT prolonged more frequently than the aPTT (98.2 vs 39.3%, P < 0.0001). After the mixing study, seven patients maintained abnormal aPTT and dRVVT ratios, five of whom had prolonged mixture with both tests. The agreement in the mixing study between aPTT and dRVVT was substantial (kappa = 0.78, 95% confidence interval = 0.48-1.00). Except for one patient, the aPTT screened all cases that demonstrated phospholipid dependency of their inhibitor during the confirmatory procedure with the dRVVT. In conclusion, the aPTT using Platelin LS was highly associated with the presence of lupus anticoagulant detected by the dRVVT among patients with venous thromboembolism, and could be reliably employed as a screening assay for lupus anticoagulant.     

Haemostatic factors associated with vascular thrombosis in patients with systemic lupus erythematosus and the lupus anticoagulant.

To elucidate the mechanism of vascular thrombosis in patients with systemic lupus erythematosus and the lupus anticoagulant changes in factors associated with haemostasis were investigated. The lupus anticoagulant was associated with an increased incidence of thrombosis, particularly cerebral thrombosis. Concentrations of fibrinopeptide A and fibrinopeptide B beta 15-42 were significantly raised in the plasma of patients with systemic lupus erythematosus and the anticoagulant compared with concentrations in patients without the lupus anticoagulant. The tendency towards formation of thrombosis was not found in all lupus patients with the anticoagulant, however. Concentrations of thromboxane B2 were remarkably raised in the plasma of the two patients with the lupus anticoagulant who had recently had thrombosis. Concentrations of 6-keto-prostaglandin F1 alpha, protein C, antithrombin III, and plasminogen were similar in both groups. No significant decrease in serum stimulatory activity on prostacyclin production by cultured aortic endothelial cells was noted in lupus patients with the anticoagulant, but inhibition was present in the two patients with recent thrombosis. These results indicate that although patients with the lupus anticoagulant are not always in a hypercoagulable state, haemostatic abnormalities found in some patients with the anticoagulant may be predictive of thrombotic events.     

Lupus pregnancy. II. Unusual pattern of hypocomplementemia and thrombocytopenia in the pregnant patient

To explore the causes of complications in pregnant women with systemic lupus erythematosus (SLE), we prospectively evaluated 34 pregnancies in 28 SLE patients, and 2 additional pregnancies in patients with lupus anticoagulant and positive antinuclear antibody, but no other manifestations of SLE. Nineteen pregnancies (55%) were complicated by marked proteinuria, thrombocytopenia, and/or lupus anticoagulant. Hypocomplementemia occurred in 18 pregnancies (52%). Neither thrombocytopenia-anticoagulant nor proteinuria was accompanied by an increase in antibody to double-stranded DNA or by clinical signs of active SLE. Antibody to Ro antigen did not predict fetal death. Both thrombocytopenia and proteinuria appeared abruptly during pregnancy and disappeared quickly after delivery. Fetal death was the result in 7 of 9 (77%) pregnancies in patients with anticoagulant, 6 of 10 (60%) in patients with thrombocytopenia, 6 of 18 (33%) in patients with hypocomplementemia, and 3 of 11 (27%) in patients with proteinuria. Twenty of 29 (68%) children were identified as male. The pathogenesis of hypocomplementemia was evaluated by a new assay, C1s-C1 inhibitor complex, which is thought to measure rate of complement activation by the classical pathway. Most pregnant patients with low CH50 levels and proteinuria had normal levels of C1s-C1 inhibitor complex, whereas nonpregnant patients with equivalent proteinuria and hypocomplementemia had high levels, as did pregnant patients with hypocomplementemia who did not have SLE. Pregnant and nonpregnant hypocomplementemic patients with proteinuria had similar levels of C3 and C4. In pregnant patients with SLE, C1s-C1 inhibitor complex was independent of CH50; in nonpregnant patients a linear relationship between C1s-C1 inhibitor complex and CH50 was seen.(ABSTRACT TRUNCATED AT 250 WORDS)     

The activated seven lupus anticoagulant assay detects clinically significant antibodies.

Lupus anticoagulants are a heterogeneous group of autoantibodies detected by their effects on phospholipid-dependent coagulation assays. Persistent lupus anticoagulants are associated with thrombotic disease, but not all are clinically significant. Antibody heterogeneity and reagent and test variability dictate that at least 2 tests, of different types, should be used to screen lupus anticoagulants. The objective of this study was to investigate whether the activated seven lupus anticoagulant assay detects clinically significant antibodies. Eighty-two patients with antiphospholipid syndrome (APS) and 32 with systemic lupus erythematosus + positive for activated seven lupus anticoagulant and who were without thrombosis, who were positive by activated seven lupus anticoagulant assay, were investigated for lupus anticoagulants by dilute Russell's viper venom time, dilute activated partial thromboplastin time, and Taipan snake venom time, and for anticardiolipin antibodies. Fifty-seven of the APS patients were positive for lupus anticoagulants in multiple assays, 25 in activated seven lupus anticoagulant alone. Fourteen of the latter group were previously positive in other antiphospholipid antibodies assays, and 11 had only been positive for lupus anticoagulants by activated seven lupus anticoagulant. Twenty-eight had elevated anticardiolipin antibodies, 6 of whom were from the group that was positive in activated seven lupus anticoagulant only. Eight of the systemic lupus erythematosus + lupus anticoagulants (without thrombosis) patients were positive for lupus anticoagulant by activated seven lupus anticoagulant alone and had only been positive in activated seven lupus anticoagulant previously, and none had elevated anticardiolipin antibodies. The remaining 24 patients were lupus-anticoagulant positive in multiple assays, and 9 had elevated anticardiolipin antibodies. Dilute Russell's viper venom time and Dilute activated partial thromboplastin time are widely used to detect lupus anticoagulants and are considered to detect clinically significant antibodies. Activated seven lupus anticoagulant detected antibodies in APS patients who were positive by these assays and also lupus anticoagulants undetectable by the dilute Russell's viper venom time/dilute activated partial thromboplastin time reagents used, demonstrating its utility as a first-line or second-line assay.     

Risk factors for thrombosis in lupus patients.

Lupus anticoagulant, concentrations of anticardiolipin antibodies, antithrombin III, plasminogen, (free) protein S, protein C, prothrombin, platelet counts, and bleeding times were determined in 74 lupus patients (58 with systemic lupus erythematosus; 16 with lupus-like disease) to establish the presence of risk factors for thrombosis in these patients. Of the variables evaluated, lupus anticoagulant had the strongest association with a history of thrombosis. Both positive anticardiolipin antibody concentrations and the presence of (mild) thrombocytopenia were significantly associated with a history of thrombosis and the presence of lupus anticoagulant. Reduced concentrations of antithrombin III, plasminogen, (free) protein S, and protein C were found in some patients but were not associated with either thrombosis or lupus anticoagulant. Mean concentrations of total protein S were significantly lower in patients with thrombosis than in those without and in patients with lupus anticoagulant than in those without. The antigenic concentration of prothrombin was reduced in 3/74 (4%) lupus patients. These three patients had lupus anticoagulant but no history of thrombosis, which suggests that a low prothrombin concentration protects patients with lupus anticoagulant from the development of thrombosis. A prolonged bleeding time was associated with the presence of lupus anticoagulant but not with a history of thrombosis. Analysis by stepwise logistic regression did not disclose additional risk factors for thrombosis in lupus patients with lupus anticoagulant. Increased antithrombin III concentrations and decreased free protein S concentrations are often found in lupus patients, unrelated to lupus anticoagulant or thrombosis.     

Purification and kinetic studies on a circulating anticoagulant in a suspected case of lupus erythematosus.

A circulating anticoagulant in a suspected case of lupus erythematosus has been highly purified by a combination of Sephadex gel filtration and DEAE cellulose chromatography. The inhibitor is a gamma globulin with a sedimentation coefficient of 6.6 Svedberg units. For its anticoagulant action, the lupus inhibitor requires a co-factor which is present both in the lupus and normal blood. The cofactor is located in the gamma globulins fraction which is relatively heat stable, but less than the inhibitor, at 56 degrees C. The active lupus inhibitor (inhibitor + cofactor) is not species specific against human prothrombin. Working with highly purified systems, the active inhibitor is found to inhibit prothrombin conversion by formed prothrombin activator. It does not appear to inhibit the formation of prothrombin activator nor does it affect purified prothrombin.     

Circulating anticoagulant of the antiprothrombinase type. Retrospective study of 134 cases

A retrospective study of 134 cases of circulating "lupus anticoagulant" (LA) observed between 1975 and 1985 in the haemostasis laboratory of Henri Mondor Hospital is reported. In 66 p. 100 of cases the circulating anticoagulant was discovered fortuitously and auto-immune diseases were associated with the inhibitor only in 25 p. 100 of cases (mainly systemic lupus erythematosus). Thrombosis (venous, arterial or both) was found in 26 p. 100 of cases when auto-immune diseases were present and in 13.5 p. 100 of cases in the absence of these diseases. Spontaneous abortion was observed in 42 p. 100 of the women when the anticoagulant occurred in the course of an auto-immune disease and in 4 p. 100 when another or no underlying disease were identified. False-positive VDRL and thrombocytopenia were found associated with LA mainly in auto immune diseases. Anticardiolipin antibodies were positive in 37 p. 100 of 32 patients without any difference between auto-immune diseases and other pathologies. These results show that the "lupus anticoagulant" is a frequent coagulation abnormality even when auto-immune diseases are absent. The differences observed between auto-immune diseases and other pathologies in respect to clinical manifestations and biological findings associated with lupus anticoagulant suggest that the so-called "lupus anticoagulant" represents a group of antibodies with probably different specificities but which act in a similar manner in "in vitro" coagulation tests.     

Evaluation of the phospholipid-rich dilute Russell's viper venom assay to monitor oral anticoagulation in patients with lupus anticoagulant.

The International Normalized Ratio (INR) is generally recommended to monitor anticoagulant therapy in patients treated with warfarin. However, there has been concern about the validity of the INR to monitor warfarin therapy in patients with lupus anticoagulant, particularly when there is prolongation of the baseline INR. An alternative approach is to use a chromogenic factor X assay that is not sensitive to lupus anticoagulant. However, this assay is expensive, not widely available, and does not have an established therapeutic range. We hypothesized that the phospholipid-rich dilute Russell viper venom time (prdRVVT), a simple, rapid and inexpensive assay, might be suitable to monitor warfarin therapy in this situation since Russell's viper venom directly activates coagulation factor X while the phospholipid in the reagent reduces or negates any effect of lupus anticoagulant on the assay. We measured the INR, chromogenic factor X, and prdRVVT in 50 patients stabilized on warfarin for at least 6 weeks, 12 of whom had lupus anticoagulant, and 37 patients not taking warfarin, 17 of whom had lupus anticoagulant. Factor X was negatively correlated with INR in anticoagulated patients both in the absence (r = -0.45, P = 0.01) and presence (r = -0.43, P = 0.17) of lupus anticoagulant. The prdRVVT was also strongly correlated with INR in anticoagulated patients without lupus anticoagulant (r = 0.60, P < 0.0001) but there was no correlation in the presence of lupus anticoagulant (r = -0.13, P = 0.68). Our results suggest that the prdRVVT is not suitable for monitoring warfarin therapy in patients with lupus anticoagulant.     

Lupus anticoagulant: clinical significance in anticardiolipin positive patients with systemic lupus erythematosus.

The significance of anticardiolipin antibodies and the lupus anticoagulant was studied in 58 consecutive patients with systemic lupus erythematosus. On 85 occasions serum IgG and IgM anticardiolipin antibodies were measured by an enzyme linked immunosorbent assay (ELISA), and simultaneous plasma samples tested for lupus anticoagulant activity. The most significant association with clinical events (previous thrombosis or thrombocytopenia occurring in 11/58 patients) was with prolonged tissue thromboplastin inhibition time (TTIT) followed by prolonged kaolin cephalin clotting time (KCCT) then raised IgG anticardiolipin antibody concentrations and dilute Russell's viper venom time. Although IgG anticardiolipin antibodies or KCCT were the most sensitive tests in identifying this group, the TTIT was the most specific (98%). Nine patients were IgG anticardiolipin antibody positive and lupus anticoagulant negative, of whom one had thrombocytopenia but none had thrombosis. The presence of a lupus anticoagulant in anticardiolipin antibody positive patients increases specificity for certain adverse clinical events.     

Monitoring Therapy with Vitamin K Antagonists in Patients with Lupus Anticoagulant: Effect on Different Tests for INR Determination

Background: Lupus anticoagulant (antiphospholipid antibodies) is associated with venous and arterial thrombosis in patients with and without autoimmune disorders. Vitamin K antagonists are the treatment of choice in patients with thrombosis, of which the dose is titrated by INR monitoring. Several recent reports suggest that the presence of the lupus anticoagulant disturbs the INR test and may lead to unreliable results with a large variation in INR values, dependent on the reagents used.Methods: We studied 11 lupus anticoagulant positive patients and 11 lupus anticoagulant negative patients, all using vitamin K antagonists. The INR value was determined using seven different tests and the variation in INR values was compared between the two groups. The amidolytic Factor X levels were used as an phospholipid independent measure for intensity of warfarin therapy. Factor VII and X activity were measured to assess the stability of warfarin therapy.Results: The variation of the results with different INR tests within one patient was minimal and comparable in the two groups for INR's in the therapeutic range. The coefficient of variation for the cases and control group was 10.43 and 9.35, respectively. Variation in both groups increased at supratherapeutic levels of anticoagulation and when the anticoagulation was unstable (measured with Factor X/Factor VII ratio). The relationship between INR values and Factor X analysis revealed no influence of the lupus anticoagulant.Conclusions: In this study, lupus anticoagulant antibodies do not disturb INR laboratory tests. Differences in INR measurements are seen in patients with a high intensity of anticoagulation and in patients who either just started or in whom no stable anticoagulation has been achieved.Abbreviated Abstract. This study investigates the influence of lupus anticoagulant on INR determination tests in patients treated with warfarin. Eleven cases and eleven lupus anticoagulant negative control patients, also on warfarin therapy, were included. Seven INR results per patient were obtained using different laboratory tests. A factor X assay was performed to obtain an independent measure for the intensity of warfarin therapy.The variation of INR results between the cases and controls revealed no difference in these groups. In addition, the relationship between INR values and Factor X analysis indicated no influence of the lupus anticoagulant. What was observed was an increased difference in INR values in patients with a high intensity of anticoagulation and in patients who either just started or in whom no stable anticoagulation has been achieved     

Immunoadsorbent plasmapheresis for a patient with antiphospholipid syndrome during pregnancy.

The case of a 34 year old woman with systemic lupus erythematosus with a history of three previous recurrent abortions and lupus anticoagulant and anticardiolipin antibodies is reported. Immunoadsorbent plasmapheresis with a dextran sulphate column was used to remove lupus anticoagulant, anticardiolipin antibodies, and antibodies to DNA during her fourth pregnancy in combination with low doses of aspirin and prednisolone. Although during the course of treatment prednisolone was transiently increased to 30 mg/day owing to an asymptomatic increase of lupus anticoagulant and anticardiolipin antibodies, the levels of lupus anticoagulant, anticardiolipin antibodies, and antibodies to DNA were decreased by immunoadsorbent plasmapheresis and a baby girl was delivered successfully by caesarean section. Therefore, immunoadsorbent plasmapheresis with dextran sulphate seems to reduce the risk of recurrent abortion in patients with the antiphospholipid syndrome.     

Occlusion of small hepatic veins associated with systemic lupus erythematosus with the lupus anticoagulant and anti-cardiolipin antibody

We report the case of a woman with lupus anticoagulant-positive systemic lupus erythematosus who developed small hepatic vein occlusion. Since the age of 34, she had been known to have hepatomegaly. A definitive diagnosis of systematic lupus erythematosus was made eight years later. Histological evaluation of the liver biopsy specimen was not fully diagnostic of prominent hepatomegaly during this period. Occlusion of the small hepatic veins was confirmed by hepatic venography, but the lumen of the large hepatic veins showed a smooth appearance. The lupus anticoagulant and anti-cardiolipin antibody were both positive. Since a high incidence of thromboembolic diseases in patients with the lupus anticoagulant or anti-cardiolipin antibody has been reported, the presence of this type of anticoagulant may provide an explanation for hypercoagulability and subsequent development of hepatic vein thrombosis in this patient. This is the first report of a patient with systemic lupus erythematosus who developed an occlusion of small hepatic veins attributable to the lupus anticoagulant and anticardiolipin antibody. This case suggested that a systematic search for hepatic vein occlusion should be made in patients with systemic lupus erythematosus who have developed inexplicable hepatomegaly, especially in those with positive tests for the lupus anticoagulant and/or anti-cardiolipin antibody.     

LIFE-THREATENING HAEMORRHAGE IN A PATIENT WITH RHEUMATOID ARTHRITIS AND A LUPUS ANTICOAGULANT COEXISTING WITH ACQUIRED AUTOANTIBODIES AGAINST FACTOR VIII

A case history of a patient with RA and a lupus anticoagulantcoexisting with an acquired inhibitor to factor VIII is described.The factor VIII inhibitor was heralded by life-threatening haemorrhagewhich followed an invasive procedure. KEY WORDS: Lupus anticoagulant, Factor VIII, Inhibitor, Bleeding, Rheumatoid arthritis     

Interaction between platelets and lupus anticoagulant

10 consecutive patients fulfilled the diagnostic criteria for lupus anticoagulant. 4 had concomitant systemic lupus erythematosus, 1 Waldenstrom's disease and 5 had no apparent underlying disease. Only the case with Waldenstrom's disease presented a bleeding tendency, with bleeding time greater than 20 min; the others had a history of thrombotic complications. A defect of platelet aggregation induced by ADP, epinephrine, collagen and arachidonic acid was documented in the Waldenstrom's disease case whose lupus anticoagulant was an IgM. In the others, lupus anticoagulant, identified as IgG immunoglobulins, produced no aggregation abnormalities. However, beta-thromboglobulin levels in platelets, plasma and urine were consistent with a pattern of platelet activation in all cases. IgG immunoglobulins separated from sera of 6 patients showed lupus anticoagulant activity, with no effects on platelet aggregation of normal platelet-rich plasma, but they induced secretion of beta-thromboglobulin from normal platelets.     

The lupus anticoagulant and its role in thrombosis

The lupus anticoagulant is usually found in the plasma of patients with systemic lupus erythematosus. Lupus anticoagulants are antibodies to phospholipids and probably to phosphodiester-linked phosphate groups. A high frequency of thrombotic events in patients with lupus anticoagulant has been reported. Nevertheless the pathogenesis of thrombosis in these patients remains unknown. Endothelium which plays a key role in the antithrombogenic-thrombogenic balance could be a target for the lupus anticoagulant and alterations of some endothelial-cell functions could be responsible for the thrombotic events. The effects of the lupus anticoagulant on the phospholipids of the protein C-thrombomodulin complex may be important although evidence of such a reaction in vivo is awaited.