Thrombosis In Systemic Lupus Erythematosus Patients Research Articles

Evaluation of acquired and hereditary risk factors for the development of thromboembolism in patients with systemic lupus erythematosus.

Although the contribution of antiphospholipid antibodies (aPL) to thrombolembolism in systemic lupus erythematosus (SLE) is well known, there is not enough data on the contribution of various hereditary thrombophilic factors. In this study, we aimed to determine acquired and hereditary thrombophilic factors in adult patients with SLE. A total of 93 SLE patients (87 women and 6 men) were included. Data on clinical, demographic and laboratory characteristics, and disease activity scores (SLEDAI) of the patients were evaluated. The patients were analyzed with a screen, including lupus anticoagulant, anticardiolipin antibodies (aCL), antithrombin III, protein C, protein S, and homocysteine levels; factor V Leiden ( FVL ), methylenetetrahydrofolate reductase ( MTHFR ) and prothrombin G20210A gene mutations. A total of 23 thromboembolic events were reported in 17 (18.3%) of the patients. The frequency of pregnancy complications and SLEDAI scores were significantly higher in SLE patients who had a thromboembolism event ( P < 0.05). Thromboembolism was detected in 12 (32.4%) of 37 patients with positive aPL antibody and 5 (8.9%) of 56 patients with negative aPL antibody ( P = 0.006). In addition, thromboembolism developed in 11 (32.3%) of 34 lupus anticoagulant-positive patients and 6 (10.1%) of 59 lupus anticoagulant-negative patients ( P = 0.012). Moreover, protein C levels were significantly lower in patients who developed thromboembolism ( P < 0.05). Patients with and without thromboembolism were similar in terms of genetic thrombophilia factors ( MTHFR A1298C, MTHFR C677T, FVL and Prothrombin G20210A ) ( P > 0.05). In conclusion, in the current study, some acquired (aPL, lupus anticoagulant and cCL IGG) and hereditary (protein C deficiency) thrombophilic factors were shown to be associated with the development of thrombosis in SLE patients. However, the effect of other hereditary factors on the development of thromboembolism could not be demonstrated. According to the data of this study, genetic screening seems inappropriate in terms of the risk of thromboembolism in patients with SLE.

Procoagulant microparticles are associated with arterial disease in patients with systemic lupus erythematosus.

Microparticles (MPs) have been associated with inflammatory and thrombotic disease. High levels of MPs have been identified in patients with systemic lupus erythematosus (SLE) and associated with cardiovascular disease. We analyzed the procoagulant activity of MPs and itscorrelation with arteriosclerosis and arterial thrombosis in SLE patients. Eighty-seven patients with SLE were included: 22 (25.3%) with associated antiphospholipid syndrome (APS), 32 (36.8%) without antiphospholipid antibodies (aPL) and 33 (37.9%) with aPL but without APS. Subclinical arteriosclerosis, defined as the presence and number of plaques, was evaluated by ultrasonography of carotid arteries. Thrombotic events were confirmed by objective methods. The procoagulant activity of MPs was determined by a functional assay with annexin V. Subclinical arteriosclerosis was found in 19 (21.8%) patients. Thirteen episodes of arterial thrombosis and eight of venous thrombosis were recorded. The procoagulant activity of MPs was greater in patients with arterial thrombosis (17.28 ± 8.29nM vs 12.96 ± 7.90nM, p < 0.05). In patients without arterial thrombosis, greater procoagulant activity of MPs was identified in patients with multiple (≥ 2) carotid plaques (17.26 ± 10.63nM vs 12.78 ± 7.15nM, p = 0.04). In the multivariate analysis, the procoagulant activity of MPs was independently associated with multiple (≥ 2) carotid plaques and arterial thrombosis [OR = 1.094 (95%CI 1.010-1.185), p = 0.027 and OR = 1.101 (95%CI 1.025-1.182), p = 0.008; respectively]. In conclusion, the procoagulant activity of MPs is associated with arteriosclerosis burden and arterial thrombosis in patients with SLE.

SAT0203 SINGLE LAC POSITIVITY VERSUS DOUBLE AND TRIPLE POSITIVITY FOR THROMBOSIS IN SLE

Background:The antiphospholipid syndrome (APS) is defined by the development of venous and/or arterial thromboses, and pregnancy morbidity, in the presence of antiphospholipid antibodies (aPL); lupus anticoagulant, moderate-to-high titer anticardiolipin (aCL) and anti-β2-glycoprotein (aB2GPI). It has been suggested that the incidence of thromboembolic events were significantly higher in the triple positive subjects, and the rate of pregnancy loss was also significantly much higher in double positive subjects (1). On the other hand several studies showed that LAC is more highly associated with thrombosis risk (2).Objectives:We aimed to investigate the risk of thrombosis in Systemic Lupus Erythematosus (SLE) patients with single LAC positivity versus double and triple positivity in Hopkins Lupus Cohort.Methods:The Hopkins Lupus Cohort is a prospective longitudinal cohort of SLE patients ongoing since 1987. This analysis was based on cohort experience from 2003 through October 2019. Anticardiolipin and anti-Beta2 glycoprotein were defined as positive when the antibody titer exceeded 20 units. The lupus anticoagulant was determined by dilute Russell’s viper venom time (dRVVT) and confirmatory mixing studies, if prolonged. It is defined as positive if a patient had a dRVVT of 45 or more second and a positive confirm ratio of more than 1.4. For each aPL, we defined the patient as positive at a given month of follow up if they ever had a positivity in previous measures. The relationships between thrombosis and aPL were adjusted for number of prior aPL assessment.Results:There were 805 patients with a complete profile of 7 antiphospholipid antibodies, with a total of 73417 person months (6118 person years) of follow up. For any thrombosis when compared to patients with LAC positivity only, double positivity with any isotypes [1.15(0.50, 2.66) p=0.7484] and triple positivity with any isotypes [1.68(0.74, 3.80), p=0.2145] showed a higher point estimates but statistically not significant (Table 1).Table 1.Single, double and triple positive patterns and the risk of any thrombosis.PatternNumber of eventsPerson-yearsRate per 1000 person-yearsadjusted RR (95% CI)p-valueLAC positivity only1063315.81.00 (Ref)Never any aPL33258112,80.73(0.36, 1.47)0.3819any aCL positivity only67937,60.43(0.16, 1.18)0.1028any aB2GPI positivity only751713,50.78(0.30,2.05)0.6195any aCL and aB2GPI positivity only540412,40.71(0.24,2.04)0.5211LAC and ACL positivity740617,31.15(0.50,2.66)0.7484LAC and aB2GPI positivity1249024,5Triple positivity01470,01.68(0.74,3.80)0.2145Conclusion:We found that triple or double positive aPL profiles are not superior to single LAC positivity in their association with any thrombosis in SLE patients.

Elevated partial antiphospholipid score is a strong risk factor for thrombosis in patients with systemic lupus erythematosus: a validation study.

This study aims to identify risk factors for thrombosis in patients with systemic lupus erythematosus (SLE) and to validate the efficacy of the partial antiphospholipid (aPL) score for thrombosis prediction and diagnosis of antiphospholipid syndrome (APS). This study included 325 SLE patients, 188 of whom completed a follow-up of 31.01 months (range 23-48 months). Partial aPL score was calculated by adding up the individual scores for activated partial thromboplastin time (APTT), lupus anticoagulant, IgG/IgM anticardiolipin antibodies (aCL), and IgG/IgM anti-β2-glycoprotein I (anti-β2GPI). A simplified aPL score was developed using only APTT, IgG/IgM aCL, and IgG/IgM anti-β2GPI. Partial aPL scores were significantly higher in SLE patients with thrombosis (p < 0.0001). A history of thrombosis (p < 0.0001), a partial aPL score >10 (p < 0.0001), and immunosuppressant use (p = 0.012) were independent risk factors for thrombosis. For patients with a history of thrombosis, partial aPL score was the strongest risk factor for recurrent thrombosis (p < 0.0001, odds ratio = 30.34 (95 % CI 7.70-118.81)). For APS diagnosis, the area under the receiver-operating characteristic curve (AUC) was 0.809 (95 % CI 0.73-0.89) using the partial aPL score. Similarly, the simplified aPL score was significantly associated with thrombosis (p < 0.0001) and was acceptable for APS diagnosis (AUC 0.797, 95 % CI 0.72-0.88). An elevated partial aPL score is a strong risk factor for thrombosis in SLE patients and is a useful tool to predict recurrent thrombosis. Partial aPL score and simplified aPL score, although comprising fewer items than the original aPL score, also represent valuable quantitative indices for APS diagnosis.

Lupus nephritis and Raynaud’s phenomenon are significant risk factors for vascular thrombosis in SLE patients with positive antiphospholipid antibodies

This study is aimed to determine the predictors of nongravid vascular thrombosis in systemic lupus erythematosus (SLE) patients with positive antiphospholipid antibodies (SLE-aPL). A cohort of 67 SLE-aPL patients who had at least one positive test for lupus anticoagulant (LA), anticardiolipin (aCL), or anti-beta2glycoprotein-1(B2) was examined. Main outcome was the presence of vascular thrombosis. Association between thrombosis and risk factors was examined by contingency table. The odds ratio (OR) of significant predictors was determined by logistic regression. Three percent of patients were LA(+), 6% were aCL(+), 31% were B2(+), 3% were aCL(+)LA(+), 35.8% were aCL(+)B2(+), 7.5% were LA(+)B2(+), and 13.4% were positive for all tests. As for clinical manifestations, 79% had lymphopenia, 76% had lupus nephritis (LN), 41.8% had autoimmune hemolytic anemia, 34.3% had thrombocytopenia, 20.9% had abortion, and 19.4% had Raynaud's phenomenon (RP). Thrombosis occurred in 26 patients. The prevalence of thrombosis for SLE-aPL was 38.8%. Thrombosis was observed more frequently in patients with LA(+) (12 of 18) than the others (14 of 49; p = 0.01). Two-by-two table showed that oral contraceptive and LN were significantly associated with increased risk of thrombosis, while lymphopenia and antimalarials were significantly associated with decreased risk of thrombosis. Multivariate analysis confirmed that LN and RP were associated with increased risk of thrombosis (OR = 6.2 and 3.2; p = 0.005 and 0.008), while lymphopenia and antimalarials were associated with decreased risk of thrombosis (OR = 0.86 and 0.18; p = 0.02 and 0.034). LA is the strongest test to determine the risk of thrombosis in SLE-aPL. The presence of LN and RP strongly predicts thrombosis, while lymphopenia and antimalarials are protective. These findings help to identify patients who may benefit from prophylactic therapy.

Anti-prothrombin antibodies predict thrombosis in patients with systemic lupus erythematosus: a 15-year longitudinal study.

To evaluate the role of anti-prothrombin (anti-PT) antibodies in predicting thrombosis in patients with systemic lupus erythematosus (SLE). An inception cohort of 101 SLE patients (12 males, 89 females; mean age 30 +/- 8 years), was considered. Clinical and laboratory evaluations were regularly performed during a 15-year follow-up (median 108 months) with a special focus on thromboembolic events. Serum samples were collected at time of diagnosis and at least once a year thereafter. IgG and IgM anti-PT, anti-cardiolipin (aCL) and anti-beta(2)glycoprotein I (beta(2)GPI) antibodies were measured by enzyme-linked immunosorbent assay (ELISA); lupus anticoagulant (LAC) was assayed by the dilute Russell's viper venom time and activated partial thromboplastin time tests. The analytical specificity of anti-PT ELISA was investigated. The timing of thrombosis occurrence was calculated using the Kaplan-Meier method. In the 15-year follow-up, thrombosis occurred in 14 out of the 101 patients: venous thrombosis in nine cases and arterial thrombosis in five. IgG and/or IgM anti-PT, anti-beta(2)GPI and aCL antibodies, and LAC activity were detected in ten, nine, seven, and nine cases, with sensitivity for thrombosis of 71.4%, 64.3%, 50% and 64.3%, respectively. Thrombosis-free survival was 90% at 5 years and 85.8% at 10 and 15 years, respectively. Thrombosis was predicted by anti-PT (P = 0.001), anti-beta(2)GPI antibodies (P = 0.002) and LAC activity (P = 0.001). Moreover, the risk of thrombosis progressively increased with the number of positive antiphospholipid antibody tests. The presence of four positive antibody tests was associated with a risk of thrombosis thirtyfold higher than in their absence. This longitudinal study shows that IgG anti-PT antibodies are predictors of thrombosis in SLE patients.

Clinical manifestations and antiphosphatidylserine antibodies in patients with systemic lupus erythematosus: is there an association?

Antiphospholipid antibodies are a group of heterogeneous autoantibodies which have been reported in systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) in association with thrombosis, fetal loss, and thrombocytopenia. In this study, we aimed to reveal the prevalence and correlation of IgG, IgA, and IgM isotypes of antibodies to cardiolipin (aCL) and antiphosphatidylserine (aPS) with clinical and laboratory manifestations of SLE patients. Fifty-nine SLE patients and 41 healthy controls were included. Fifteen of patients (25.4%) had secondary APS. aCL and aPS antibody assays were performed by enzyme-linked immunosorbent assay. All isotypes of aCL and aPS antibodies except IgG were higher in patients with or without APS than those in the healthy controls (p<0.001). The most significant associations were found among migraine and IgA aCL (p<0.001), livedo reticularis and both IgM aCL and IgM aPS (p<0.001), migraine and IgM aCL (p<0.01), pulmonary involvement and IgM aCL (p<0.01), migraine and IgA aPS (p<0.01), and both thrombosis and migraine with IgM aPS (p<0.01). A relatively high prevalence of aCL and aPS antibodies was found in our SLE patients. It seems that isotypes of IgM aCL, IgM aPS, IgA aCL, and IgA aPS antibodies are correlated well with migraine and IgM aPS with thrombosis in SLE patients with secondary APS. The assessment of both IgM and IgA isotypes of aPS and aCL antibodies may be helpful in predicting these manifestations.

Prevalence and Clinical Correlation of Anti-Phospholipid–Binding Protein Antibodies in Anticardiolipin-Negative Patients With Systemic Lupus Erythematosus and Women With Unexplained Recurrent Miscarriages

Anti-phospholipid antibodies (aPL) are a heterogeneous group of autoantibodies, the presence of which is associated with thrombotic events and miscarriage. To establish whether antibodies directed against phospholipid-binding plasma proteins such as beta(2)-glycoprotein I (beta(2)GPI), prothrombin (PT), and annexin V (Anx V) constitute a risk factor for thromboembolism in patients with systemic lupus erythematosus (SLE) and for miscarriage in women with recurrent pregnancy loss (RPL), independently of the presence of the classic anticardiolipin (aCL) antibodies, and whether their determination together with that of aCL would help to increase the diagnostic sensitivity of aPL tests. The prevalence of various antibodies directed toward phospholipids (CL and other anionic phospholipids [APL]) and phospholipid-binding proteins (beta(2)GPI, PT, and Anx V) was determined by immunoenzymatic methods in 311 serum samples. Twenty-five patients with aCL-positive primary anti-phospholipid syndrome (pAPS); 89 patients with SLE, 23 of whom had thrombotic complications (SLE/APS) and 66 of whom had no thrombosis; and 77 women with unexplained recurrent pregnancy loss comprised our study group. One hundred twenty healthy subjects matched for age and sex were studied as the control group. Immunoglobulin (Ig) G and/or IgM aAPL, anti-beta(2)GPI, anti-PT, and IgG anti-Anx V antibodies were detected in 25 (100%), 20 (80%), 15 (60%), and 6 (24%), respectively, of the 25 aCL-positive pAPS patients; IgG and/or IgM aCL, aAPL, anti-beta(2)GPI, anti-PT, and IgG anti-Anx V antibodies were detected in 33 (37%), 42 (47%), 31 (35%), 40 (45%), and 12 (13%) of the 89 SLE patients, respectively. Of the 56 SLE patients who proved to be aCL negative, anti-beta(2)GPI was present in 3 patients (5%), anti-PT in 13 (23%) patients, and anti-Anx V in 5 (9%) patients. In the subset of 23 SLE/APS patients, IgG anti-PT prevalence was higher than that of the other autoantibodies (87% vs 70% aCL, 66% aAPL, 57% anti-beta(2)GPI, and 4% anti-Anx V), and in 26% of cases, IgG anti-PT was the only antibody present. Anti-PT had a slightly lower specificity than aCL (46% vs 49%); however, the occurrence of both antibodies brought the specificity to 92.4%. The highest risk for thrombosis in SLE patients was associated with the presence of IgG anti-PT antibody (odds ratio [OR] 15.3, P < .001, vs 6.5 aCL, 3.5 aAPL, 3.4 anti-beta(2)GPI, 0.2 anti-Anx V). Fifty-one of the 77 women with recurrent pregnancy loss were negative for all antibodies investigated; the prevalence of IgG and/or IgM aCL, aAPL, anti-beta(2)GPI, anti-PT, and IgG anti-Anx V antibodies was 6% (5), 12% (9), 6% (5), 16% (12), and 17% (13), respectively. Of the 67 aCL-negative women, none had anti-beta(2)GPI antibodies, 7 (11%) were anti-PT positive, and 13 (19%) were anti-Anx V positive. In the subgroup of 26 recurrent pregnancy loss patients who had at least one antibody, anti-Anx V was present in 50% of cases (in 42% as the sole antibody) and was the only antibody significantly associated with miscarriage (P = .02). The results of this study indicate that it is useful to measure anti-PT antibodies in addition to the more widely used aCL and anti-beta(2)GPI antibodies in the prognostic evaluation of SLE patients for the risk of thrombosis, and the results also confirm that anti-Anx V antibodies may play an important role in recurrent pregnancy loss.

Autoantibodies recognizing the 27 carboxy-terminal amino acids of calpastatin are associated with secondary Sjögren syndrome in systemic lupus erythematosus

The objective of this study was to determine in systemic lupus erythematosus (SLE) the prevalence and clinical significance of anticalpastatin antibodies (ACAST), an autoantibody population previously detected in sera from patients with various connective tissue diseases. Eighty-four patients with SLE (mean age: 30 years at diagnosis, females 77) that fulfilled ACR criteria were included in the study retrospectively. Several clinical and biological data were collected. ACAST were detected by a solid-phase enzyme linked immunosorbent assay (ELISA) using as antigen a synthetic peptide corresponding to the 27 C-terminal amino acids of calpastatin (CAST-C27). The prevalence of ACAST-C27 was 13% (11/84) in SLE patients. No correlation was found between the presence of ACAST-C27 and clinical manifestations such as thrombosis and vasculitis. Furthermore, no correlation was observed with the presence ofantiphospholipid antibodies (APL). However, we found a statistically significant association between the presence of ACAST-C27 and that of secondary Sjögren syndrome (P = 0.01). The conclusion is ACAST-C27 are not associated with thrombosis in SLE patients. The association observed between ACAST-C27 and secondary Sjögren syndrome suggests that ACAST-C27 might be useful in discriminating a clinical subgroup of SLE patients.

Acquired activated protein C resistance, high tissue factor expression, and hyper‐homocysteinemia in systemic lupus erythematosus

Activated protein C resistance (APCR), high tissue factor (TF) expression, and hyper-homocysteinemia are associated with thromboembolic diseases. Thromboembolism is a frequent complication of systemic lupus erythematosus (SLE). In this study, we evaluated the prevalence of APCR, high TF, and homocysteine with correlation of the thrombotic tendency in SLE. Ninety-four SLE patients and 28 normal controls were included. APC ratio and TF antigen were measured using commercial kits. Plasma homocysteine level was measured using HPLC. The prevalence of APCR, high TF antigen level, and hyper-homocysteinemia in our SLE patients were 21.3%, 66.0%, and 23.4%, respectively. The median plasma level of TF antigen in SLE patients was 145.23 pg/mL (range, 31.00-778.50 pg/mL), which was significantly higher than the control value of 39.83 pg/mL (range, 1.55-168.50 pg/mL). The median APC ratio in SLE patients was 2.76 (range, 1.48-13.47), which was significantly lower than the control value of 3.59 (range, 0.26-5.66). The plasma level of homocysteine was not significantly different from that of control. A significant association was observed between the presence of APCR (OR = 8.59, P < 0.0001) but not with the presence of high plasma TF antigen level (OR = 1.24, P = 0.67) and thrombotic complications in SLE patients. In conclusion, APCR and high plasma TF levels are common in SLE, but a significant association was observed only between the presence of APCR and thrombosis in SLE patients.

Strong association of autoantibodies to human nuclear lamin B1 with lupus anticoagulant antibodies in systemic lupus erythematosus.

To determine the frequency and clinical significance of high titers of IgG autoantibodies to nuclear lamin B1 in a large number of unselected and well-characterized systemic lupus erythematosus (SLE) patients, disease controls, and normal healthy controls. A cross-sectional study of anti-lamin B1 autoantibodies, as measured by enzyme-linked immunosorbent assay using human recombinant lamin B1 autoantigen, was performed on serum samples obtained at first evaluation of 238 consecutive French Canadian adults: 61 healthy control subjects, 20 patients with osteoarthritis, 22 with ankylosing spondylitis, 11 with autoimmune hepatitis, 30 with rheumatoid arthritis, and 94 with SLE. SLE patients were studied for 57 disease manifestations. A case-control study was performed to analyze the relationship between anti-lamin B1 status and thrombotic manifestations between SLE onset and last followup. High titers of anti-lamin B1 were strikingly restricted to a subset of 8 SLE patients (8.5%). The mean anti-lamin B1 titer was higher in this subset than in the other SLE patients or any control group (P<0.001). By univariate analysis and stepwise multiple logistic regression, the most striking association of anti-lamin B1 was with lupus anticoagulant (LAC) antibodies (P = 0.00001). Although LAC were significantly associated with thrombosis in our SLE patients, anti-lamin B1 was not. The frequency of thrombosis in SLE patients expressing both LAC and anti-lamin B1 was similar to that in patients without LAC (P = 1.0). However, patients expressing LAC without anti-lamin B1 had a greater frequency of thrombosis (P = 0.018). High titers of IgG anti-lamin B1 autoantibodies are highly specific for a subset of SLE patients whose clinical characteristics include the presence of LAC and other laboratory manifestations of the antiphospholipid syndrome. The presence of LAC without anti-lamin B1 may define a subset of SLE patients at greater risk for thrombosis.

Arterial disease in lupus and secondary antiphospholipid syndrome: association with anti-beta2-glycoprotein I antibodies but not with antibodies against oxidized low-density lipoprotein.

The prevalence and clinical significance of antibodies against beta2-glycoprotein I (anti-beta2GPI) and antibodies against oxidized low-density lipoprotein (anti-ox-LDL) were evaluated as potential indicators of arterial disease in patients with systemic lupus erythematosus (SLE) and SLE with secondary antiphospholipid syndrome (APS). IgG anti-beta2GPI and IgG anti-ox-LDL were measured by enzyme-linked immunosorbent assay (ELISA) in serum samples from 118 patients with SLE, including 40 with secondary APS. IgG anti-beta2GPI were positive in 17% (20/118) of SLE patients. The presence and titres of IgG anti-beta2GPI were strongly associated with a history of arterial thrombosis. Haemolytic anaemia was also significantly associated with the presence of IgG anti-beta2GPI. The prevalence of IgG anti-ox-LDL was 53% (63/118), but there was no association with arterial thrombosis. No correlation between the values of anti-ox-LDL and those of anti-beta2GPI was found. These results suggest that IgG anti-beta2GPI could be a marker for arterial thrombosis in SLE patients, while IgG anti-ox-LDL were not associated with arterial disease in this group of lupus patients.

Contraceptive practice in women with systemic lupus erythematosus.

Since there are few data on the use of various birth control methods in systemic lupus erythematosus (SLE), we performed a cross-sectional study of the actual contraceptive practices in a group of 85 Finnish female SLE patients of reproductive age. We also recorded side-effects experienced during the use of oral contraceptives (OCs) and intrauterine devices (IUDs). The use of contraception was lower in SLE patients than in healthy women of the same age (59 vs 77%, P < 0.001). Sexually active SLE patients requiring contraception used more often barrier and natural methods (P < 0.001) and less often OCs (P < 0.05) than the corresponding healthy women. The risk of deep venous thrombosis in SLE patients while using oestrogen-containing OCs was slightly increased (RR 2.3, 95% CI 0.5 to 10.3). Twenty-five (78%) of the 32 patients, who had used progestagen-only contraceptives discontinued them because of side effects, which were mainly gynaecological. Major bleeding or pelvic infection did not occur during the use of IUDs.

Platelet autoantibodies detected by immunoblotting in systemic lupus erythematosus: Association with the lupus anticoagulant, and with history of thrombosis and thrombocytopenia

71 patients with systemic lupus erythematosus (SLE) were studied for the occurrence of platelet antibodies by immunoblotting. Binding of IgG antibodies to platelet protein antigens was observed in 39 of the 71 patients. The most frequently detected and exceptionally strongly reacting antibodies were directed against platelet protein antigens with an approximate molecular weight of 65 kDa under nonreducing conditions. These antibodies were autoreactive and, when followed, they usually persisted. Interestingly, in this group of well-defined SLE patients, platelet antibodies against the most common targets (65 kDa) were significantly associated with the lupus anticoagulant, a history of thrombocytopenia and thrombosis, particularly with arterial occlusions. The lupus anticoagulant, on the other hand, correlated significantly only with venous thrombosis. In addition to the lupus anticoagulant, platelet antibodies against this unknown platelet protein may thus be a marker of a higher risk of thrombosis in SLE patients.

Increased Monocyte Procoagulant Activity Independent of the Lupus Anticoagulant in Patients with Systemic Lupus Erythematosus

Monocytes can play a role in the activation of coagulation via increased procoagulant activity (PCA). We investigated the level of monocyte PCA in 19 patients with systemic lupus erythematosus (SLE), given the high rate of thrombotic events in this condition. Nine of these subjects also presented the lupus anticoagulant (LA). The PCA generated by patient monocytes was significantly higher than control values and was identified as tissue factor-like. Moreover, the number of monocytes with membrane-associated D dimer, a parameter which we have shown to be correlated with the PCA expressed in vitro by endotoxin-activated monocytes, was also significantly increased. Serum from both groups of patients (i.e. SLE and SLE + LA) stimulated the generation of PCA by control monocytes. By contrast, purified IgG from both patient groups had the same effect as control IgG on PCA generation by control monocytes. The nature of the stimulating agent in the serum was not identified. In conclusion, increased monocyte PCA may account for the increased incidence of thrombosis in SLE patients, although other, superimposed, factors would appear to exist in SLE + LA patients, given the higher incidence of thrombosis in this subgroup.