AZZA H. EL-AWAR, M.D.*; TAMER M.A. GHEITA, M.D.*; DOAA H. SAYED, M.D.*; MAGDA I.M. AYOUB, M.D.** and ASMAA M. ABD-ALAAL, M.D.***

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1 Med. J. Cairo Univ., Vol. 82,. 2, December: 1-8, Relation of Immunoglobulin A Isotype of Anti -ß2 Glycoprotein I to Clinical and Laboratory s of Antiphospholipid Syndrome and Systemic Lupus Erythematosus AZZA H. EL-AWAR, M.D.*; TAMER M.A. GHEITA, M.D.*; DOAA H. SAYED, M.D.*; MAGDA I.M. AYOUB, M.D.** and ASMAA M. ABD-ALAAL, M.D.*** The Departments of Rheumatology & Rehabilitation*, Microbiology & Immunology** and Chemical Pathology***, Faculty of Medicine, Cairo University, Cairo, Egypt Abstract Introduction: Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of autoantibodies to components of the cell nucleus. Antiphospholipid syndrome (APS) is the most common type of acquired thrombophilias. The diagnosis of APS should be made on the presence of the characteristic clinical manifestations of thrombosis/pregnancy morbidity and the presence persistently positive antiphospholipid antibodies [apl] (anticardiolipin [acl] IgM/IgG or anti-ß2 glycoprotein I [anti-ß2gpi] IgM/IgG), lupus anticoagulant [LA] or both. Aim of the Work: Clarifying the significance of anti-ß2gpi of IgA isotype among Egyptian lupus with and without APS regarding clinical and laboratory features of both diseases. Patients and Methods: The study included 54 SLE. Twenty seven (50%) of those had no APS while the other half had secondary APS. Patients with other known causes of thrombophilia were excluded. Twenty seven apparently normal age and sex-matched Egyptian control persons were included. Patients were subjected to clinical assessment and routine laboratory tests. Both and controls were evaluated for the presence of lupus anticoagulant, anti- ß2GPI of IgM, IgG and IgA isotype as well as acl of IgM, IgG and IgA isotypes. Results: Dural sinus thrombosis and autoimmune thrombocytopenia were significantly more common in with positive anti -ß2GPI IgA (p-value: and 0.03 respectively). Conclusion: Anti -ß2GPI of IgA isotype seems to contribute to the pathogenesis of thrombotic and non thrombotic manifestations of SLE and APS i.e. dural sinus thrombosis and autoimmune thrombocytopenia. Key Words: Antiphospholipid syndrome Systemic lupus erythematosus Antiphospholipid antibodies Anti-ß2 glycoprotein I antibodies Anticardiolipin antibodies Lupus anticoagulant. Correspondence to: Dr. Doaa H. Sayed doaahaassan@kasralainy.edu.eg Introduction SYSTEMIC lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of autoantibodies to components of the cell nucleus. It can affect almost all organ systems with a pattern of remissions and exacerbations [1]. Antiphospholipid syndrome (APS) is the most common type of acquired thrombophilias [2]. The most common manifestation of arterial thrombosis is stroke while the most frequent type of venous thrombosis is deep venous thrombosis. Pregnancy losses in with APS typically occur after the 10th week of gestation. The diagnosis of APS should be made on the presence of the characteristic Clinical manifestations and the presence of persistently positive antiphospholipid antibodies (apl) (anticardiolipin [acl] IgM/IgG or anti -ß2 glycoprotein I [anti -ß2GPI] IgM/IgG), lupus anticoagulant [LA] or both. APS may occur in isolated form or in association with other rheumatic diseases, most commonly SLE [3]. Anti -ß2 glycoprotein I antibodies are directed against the phospholipid-binding plasma protein, ß2-glycoprotein I or apolipoprotein H [4]. The association between anti -ß2GPI and manifestations of APS is stronger than that of acl [5] and the determination of anti -ß2GPI is necessary in with features of APS who test negative for acl and LA [6]. Although IgA isotype of anti -ß2GPI antibodies is not included in the classification criteria of APS, it was found to be very frequent among SLE [7,8]. Many of lupus and experiencing pregnancy loss or thrombosis without 1

2 2 Relation of Immunoglobulin A Isotype satisfying the classification criteria for APS are positive for IgA apl alone or with other apl isotypes [9-12]. Hence, many researchers kept the enthusiasm evaluating the role of apl IgA isotype. They thought that apl IgA could help classification of experiencing manifestations highly suggestive of APS but they have apl IgA as the only positive apl. However, their work provided controversial results [6,8,10,13-19]. It was reported that there was a significantly higher frequency and level of IgA anti -ß2GPI in with SLE who have APS compared to those without [14]. Furthermore, other researchers found that measuring IgA anti -ß2GPI may be important for assessing the risk of thrombosis, especially venous thrombosis, in with SLE [6,20]. Mehrani and Petri's work concluded that the classification criteria for APS should be revised to include IgA anti -ß2GPI [21]. Recently, IgA antiß2gpi positivity was added to the Systemic Lupus International Collaborating Clinics (SLICC) Revision of the American College of Rheumatology (ACR) Classification Criteria for SLE [22]. Our study aimed at clarifying the significance of the anti -ß2GPI of IgA isotype among Egyptian lupus with and without APS regarding clinical and laboratory features of both diseases. Patients and Methods The study included 54 Egyptian SLE. Age of the ranged from years. The age of the control persons ranged from years. Four of the, all with APS, were males. Ten of the enrolled, five with APS, had juvenileonset SLE while the others developed lupus during adulthood. Age of onset ranged from years. The range of disease duration was years. SLE was diagnosed based on fulfilling the 1997 update of the 1982 American College of Rheumatology revised criteria for SLE [23,24]. Half of our were selected to have secondary antiphospholipid syndrome (SAPS) based on fulfilling the Revised preliminary Sapporo classification criteria of APS [25]. Lupus having no APS were referred to as group 1 while those suffering from APS were referred to as group 2. The were enrolled from the Rheumatology and Rehabilitation Department, Cairo University Hospital. Exclusion criteria: Known risk factors of arterial and venous thrombosis as history of smoking, diabetes mellitus, uncontrolled systemic hypertension, dyslipidemia, nephrotic syndrome and use of estrogen containing contraceptive drugs or hormone replacement therapy were excluded. Twenty seven age- and sex-matched Egyptian Healthy volunteers served as controls. Approval of the local ethical committee was obtained. All were subjected to full history taking, thorough clinical examination in addition to routine laboratory investigations. Other investigations were done when indicated. Both and controls were subjected to testing for apl: Measurement of lupus anticoagulant: Screening was done using the dilute Russell viper venom time (drvvt) which followed by a confirmatory step. The screen ratio, the ratio of screen clotting time of the tested plasma to that of the reference pool, was calculated. The confirm ratio, the ratio of confirm clotting time of the tested plasma to that of the reference pool, was calculated. The presence of lupus anticoagulant was confirmed when the normalized ratio, the ratio of the screen ratio to confirm ratio, was equal to or more than 1.2. The assay was performed using kits purchased from DIAGNOSTICA STAGO, 9, rue des Frères Chausson ASNIERES, France and analyzer of the STA line. Measurement of anticardiolipin antibodies (acl) IgA, G and M levels by ELISA using kits purchased from Demeditec Diagnostics GmbH, Lise-Meitner-Straße 2, D kiel (Germany). This assay was considered positive when Ig A/G level was greater than 10U/ml and IgM level was greater than 7U/ml. Measurement of anti -ß2GPI IgA, G and M levels by ELISA using kits purchased from Demeditec Diagnostics GmbH, Lise-Meitner-Straße 2, D kiel (Germany). This assay was considered positive when the level of antibodies was greater than 8U/ml. Assessment of SLE activity and damage: Disease activity was assessed using Systemic Lupus Erythematosus Disease activity Index (SLE- DAI) [26] and damage was assessed using the Systemic Lupus International Collaborating Clinics/ American College of Rheumatology Damage Index (SLICC/SDI) [27]. Both scores were recorded at the time of testing for apl. Statistical methods: Data were statistically described in terms of mean ± standard deviation (±SD), range, or frequencies (number of cases) and percentages when appropriate. For comparing categorical data, Chi square

3 Azza H. El-Awar, et al. 3 (χ 2 ) test was performed. Exact test was used instead when the expected frequency is less than 5. All statistical calculations were done using computer program SPSS (Statistical Package for the Social Science; SPSS Inc., Chicago, IL, USA) version 15 for Microsoft Windows. Results Demographic features and obstetric history of the patient groups and controls are shown in Table (1). Comparison between the two patient groups regarding Clinical manifestations and disease indices revealed the presence of statistically significant differences concerning APS nephropathy, venous thromboses, DVT, superficial thrombophlebitis, arterial thrombosis, digital gangrene / threatened digital ischemia and Lymphopenia where these manifestations were more common in group 2 (p-value: 0.038, 0.002, 0.002, 0.038, 0.002, and respectively). Dry mouth, discoid rash and cutaneous vasculitis were more common in group 1 than group 2 (p-value: 0.038, and respectively). SLICC-SDI was higher in group 2 than group 1 (p-value: 0.028) while there was no significant difference concerning SLE-DAI. Comparison between the two groups regarding the routine laboratory features revealed that serum albumin was lower in group 1 than group 2 (p-value: 0.006). Comparison between SLE Patients and controls regarding apl levels and positivity revealed that prolonged LA was more common in the than the controls (p-value: 0.006) and the normalized ratio was significantly higher in the than in the control group (p-value: 0.001). Positivity and level of acl IgG were significantly higher in the than the control group (p-value: and respectively). The level, but not the positivity, of acl IgA was significantly higher in the control group than the ( p-vale: 0.009). Positivity for anti -ß2GPI, in general, and IgM isotype in particular, was more common in the than the control group ( p-value: 0.02 and respectively). Moreover, the level of antiß2gpi IgA was significantly higher in the than the control group (p-value: 0.048). The comparison between the two patient groups was performed regarding the immunological laboratory features, including apl positivity and levels. LA prolongation and isolated anti -ß2GPI positivity tended to be more common in group 2 than group 1 but these differences could not reach a statistically significant value ( p-value: 0.07 and 0.09 respectively). Comparison between SLE of both groups who are positive for anti -ß2GPI IgA with those who are negative regarding obstetric morbidity and vascular events; other Clinical manifestations and laboratory features; as well as the disease duration and indices is shown in Tables (2,3,4) respectively. Dural sinus thrombosis and autoimmune thrombocytopenia were significantly more common in anti -ß2GPI IgA positive. Anti -ß2GPI IgA isotype existed in an isolated form, without other anti-ß2gpi isotypes or other apl, in a significant number of SLE without APS (18.5%) and with APS (29.6%). Dural sinus thrombosis and leukopenia were more common among with isolated anti -ß2GPI IgA positivity compared with other. Table (1): Demographic features and obstetric history of the two patient groups and the control group. Group 1 (SLE) Group 2 (SLE with APS) Demographic features N (%) Control p Value Group 1 (SLE) Group 2 (SLE with APS) Obstetric History N (%) N=27 N=27 N=27 N=18 N=18 Sex Males 0 (0) 4 (14.8) 3 (11.1) 0.1 History of pregnancy ever 18 (85.7) 16 (94.1) Female 27 (100) 23 (85.2) 24 (88.9) Disease onset: Juvenile onset 5 (18.5) 5 (18.5) Pregnancy morbidity 1 Abortion 4 (21.1) 3 (16.7) 13 (81.25) 11 (68.75) Adult onset 22 (81.5) 22 (81.5) Stillbirth 3 (16.7) 6 (37.5) Demographic features Mean (SD) IUGR 2 (11.1) 0 (0) Age in years 27.06± ± ± Preterm labor 1 (5.6) 1 (6.25) Disease duration (years) 6.7± ± Pre eclampsia 1 (5.6) 4 (25)

4 4 Relation of Immunoglobulin A Isotype Table (2): Comparison between IgA anti-ß2gpi positive of both groups with negative concerning obstetric morbidity and vascular events. Table (4): Comparison between IgA anti-ß2gpi positive of both groups with negative regarding disease duration and indices. Positive N (%) Negative N (%) p value Positive (Mean±SD) Negative (Mean±SD) p value Pregnancy morbidity Thrombosis DVT Arterial thrombosis Dural sinus thrombosis Superficial thrombophlebitis 7 (50) 7 (50) 6 (24) 19 (76) 9 (36) 16 (64) 5 (20) 20 (80) 4 (16) 21 (84) 2 (15.4) 11 (84.6) 10 (45.5) 12 (54.5) 8 (27.6) 21 (72.4) 5 (17.2) 24 (82.8) 3 (10.3) 26 (89.7) 0 (0) 29 (100) 2 (4.9) 39 (95) Table (3): Comparison between IgA anti-ß2gpi positive of both groups with negative concerning other clinical manifestations and laboratory features. Positive N (%) Negative N (%) p value Constitutional 18/72 22/ /28 7/24.1 Mucocutaneous 21/84 25/86.2 4/16 4/13.8 Musculoskeletal 21/84 28/96.6 4/16 1/3.4 Nephritis 18 (72) 21/72.4 7/28 8/27.6 Neuropsychiatric 10/40 8/ /60 21/72.4 Cardiovascular 12/48 20/69 13/52 9/31 Pulmonary 15/60 1 / /40 12/41.4 Abdominal 14/56 13/ /44 16/ Sicca 2/8 4/ /92 25/86.2 Other ocular 2/8 23/92 1/3.4 28/96.6 Leukopenia 19 (76) 16 (55.2) 6 (24) 13 (44.8) Autoimmune 16 (64) 10 (34.5) thrombocytopenia 9 (36) 19 (65.5) Anemia of 24 (96) 28 (96.6) chronic disease 1 (4) 1 (3.4) Hypo complementemia 23 (92) 23 (79.3) 2 (8) 6 (20.7) Erythrocyte sedimentation rate ± ± Disease duration SLEDAI (Mean±SD) SLICC (Mean±SD) 7.1 ± ± ± 1.2 Discussion 6.7± ± ± IgA isotype of apl were excluded from APS classification criteria based on lacking specificity and providing no additional information to those given by IgM or IgG isotypes [8]. Moreover, they are not fully standardized making it difficult to compare studies from different laboratories [9,28-31]. Furthermore, there is a considerable difference among the studied ethnicities adding difficulty to the interpretation of the results of the different studies [32-35]. Most of the studies supporting the usefulness of IgA apl are retrospective studies, case-reports and case-series making the comparison between the results of studies of different designs difficult. In addition their benefit could not be verified because they are commonly found in association with other apl [36]. Our study aimed at clarifying the significance of IgA isotype of anti-ß2gpi among Egyptian lupus without or with associated APS regarding clinical and laboratory features of both diseases. In our study, comparison between anti -ß2GPI IgA positive of both groups with negative regarding the obstetric morbidity, thrombotic manifestations, other clinical manifestations, disease duration, laboratory features as well as disease indices revealed that Dural sinus thrombosis was significantly more common in with positive anti -ß2GPI IgA. Other studies [37-39] reported that IgA apl do correlate with APS manifestations including cardiovascular disease and thrombotic events. In our study, the anti -ß2GPI isotype having the strongest association with APS and SLE manifestations was IgA; our finding is in agreement with the results obtained by Mehrani and Petri. They reported that venous thrombosis affected a higher percentage of with IgA anti -ß2GPI positivity compared with negative and the frequency of arterial and venous thromboses was higher in anti -ß2GPI IgA positive than acl IgA positive ones [20]. Many authors suggested that measuring IgA anti -ß2GPI

5 Azza H. El-Awar, et al. 5 may be considered in assessing SLE for the risk of thrombosis, especially on the venous side [6,21]. In a stepwise multivariate logistic regression analysis of another study, anti -ß2GPI IgA was determined as the strongest risk factor of venous thrombosis [37]. Although positivity of IgA anti -ß2GPI was significantly associated with thrombosis in the study done by Tsutsumi and his coworkers, their results did not directly prove a relationship between the presence of IgA anti -ß2GPI and thrombosis, they explained this finding by that most who had a history of thrombosis with positive IgA anti -ß2GPI were also positive for IgG or IgM antiß2gpi [40]. In our study, autoimmune thrombocytopenia was more common among with anti -ß2GPI IgA positivity. Our results are more or less concordant with the results of other studies that linked the association of IgA isotype of anti -ß2GPI antibody to APS manifestations in lupus including thrombocytopenia, livedo reticularis, epilepsy and heart valve disease [7,10,14,41]. In other studies, high titers of IgA apl were frequently associated with skin ulcers [42], cognitive impairment [43], Raynaud s phenomenon [44], celiac disease [45], autoimmune hepatitis [46] and transient ischemic attacks [47]. Many studies have also suggested the possible significance of assessment of IgA anti -ß2GPI [14,48-52]. Being dimeric or trimeric, IgA isotype of anti -ß2GPI could be more efficient in recruiting ß2GPI on the cell surface receptors and so being more efficient in signal transduction [53]. Furthermore, in a study of SLE, it was reported that IgA anti -ß2GPI, among the different anti -ß2GPI isotypes, was significantly associated with laboratory markers as high ESR, low C3 and anti-smith antibodies; and Clinical parameters as pulmonary hypertension and pulmonary fibrosis [21] ; however, this could not be approved in our study. In addition to the known association of antiß2gpi with the various manifestations of APS, Lakos and his colleagues stated that the association of the different anti -ß2GPI antibody isotypes with the different clinical features of APS seems to classify APS into distinct subgroups and this may be reflected on therapy [10]. On the other side, other studies have found no association between IgA anti -ß2GPI and APS man- ifestations in SLE [6,8,9,17,19,54,55]. Kumar and his colleagues stated that most positive for IgA apl are also positive for other apl isotypes [41] Moreover, Samarkos and his colleagues found that the addition of IgA apl for the diagnostic tests of APS, even, decreased the accuracy of the test [19]. Despite of the presumed pathogenic role of anti -ß2GPI IgA, the increased risk of thromboembolism in SLE with anti -ß2GPI IgA positivity could be explained by lupus flare itself as stated by many authors [8]. Moreover, in a study of lupus and others, Sweiss and his colleagues stated that isolated IgA anti -ß2GPI positivity was a risk factor of thromboembolic events. However, this increased risk persisted for lupus when they were analyzed separately; but it was not the case with other [8]. Isolation of anti -ß2GPI IgA isotype in our APS at time of recruitment may be explained by the suggestion that apl level may fluctuate with disease activity and treatment [56]. In a study of a cohort of 472 SLE, the association between LA and thrombosis has been confirmed. Importantly, both univariate and multivariate analyses showed that elevated IgA of acl and anti -ß2GPI were significantly associated with a thrombotic event, even in the absence of LA. However, multivariate analysis of the data showed no significant association between thrombosis and elevated IgG acl and anti -ß2GPI [53]. In a systematic review done in 2013, it was concluded that there was not enough evidence to recommend testing for neither IgA acl nor IgA anti- ß2GPI to increase the diagnostic accuracy of the apl testing. It was also stated that, when the association between IgA apl and thrombosis and/or pregnancy morbidity was analyzed separately in the absence of other apl in most of the studies supporting their utility, the association was lost. Moreover, it was found that when apl IgA present alone in absence of other isotypes, they were usually associated with minor APS manifestations as skin ulcers, Raynaud s phenomenon, livedo reticularis and cutaneous vasculitis [36]. Moreover, racial differences were reported to play a role in the prevalence, isotype distribution and clinical significance of acl and anti-ß2-gpi [33]. From our findings, we can conclude that evaluating SLE with manifestations highly

6 6 Relation of Immunoglobulin A Isotype suggestive for APS, but lacking all the standardized apl, for anti -ß2GPI IgA could be valuable. However, the potential benefit of anti -ß2GPI IgA deserves further studies on a larger number of with the consideration of exclusion of inherited thrombophilias, although this may not be feasible in anticoagulated. References 1- TASSIULAS I.O. and BOUMPAS D.T.: Clinical s and Treatment of Systemic Lupus Erythematosus in Kelley s Textbook of Rheumatology; 8th edition; ed. by Firestein G.S., Budd R.C., Harris E.D., Mclnnes I.B., Ruddy S. and Sergent J.S.; Elsevier Saunders; Philadelphia, , THOMAS R.H.: Hypercoagulability syndromes. Arch. Intern. Med., 161: , ERKAN D., SALMON J.E. and LOCKSHIN M.D.: Antiphospholipid syndrome in Kelley s Textbook of Rheumatology; 9th edition; ed. by Firestein G.S., Budd R.C., Gabriel S.E., Mclnnes I.B., O Dell J.R. Elsevier Saunders; Philadelphia, Volume 3, Chapter 82: , ROUBEY R.A.S.: Review Article: Autoantibodies to phospholipid-binding plasma proteins: A new view of Lupus Anticoagulants and other antiphospholipid autoantibodies. Blood, 84 (9): , TSUTSUMI A., MATSUURA E., ICHIKAWA K., FUJISAKU A., MUKAI M., KOBAYASHI S. and KOIKE T.: Antibodies to beta 2-glycoprotein I and Clinical manifestations in with systemic lupus erythematosus. Arthritis Rheum., 39: , LEE S. S., CHO M.L., JOO Y. S., HONG Y. S., MIN J.K., LEE S.H., PARK S.H., CHO C.S. and KIM H.Y.: Isotypes of Anti-ß2-Glycoprotein I Antibodies: Association with Thrombosis in Patients with Systemic Lupus Erythematosus. J. Rheumatol., 28: , DANOWSKI A., KICKLER T. and PETRI M.: Anti-ß2- glycoprotein I: Prevalence, Clinical correlations, and importance of persistent positivity in with antiphospholipid syndrome and systemic lupus erythematosus. J. Rheumatol., 33: , SWEISS N.J., RONGHAI B.O., KAPADIA R., KAPA- DIAR., MANST D., MAHMOOD F., ADHIKARI T., VOLKOV S., BADARACCO M., SMARON M., CHANG A., BARON J. and LEVINE J. S.: IgA Anti ß2 Glycoprotein I Autoantibodies Are Associated with an Increased Risk of Thromboembolic Events in Patients with Systemic Lupus Erythematosus. PLoS ONE, 5 (8): e SELVA-O CALLAGHAN A., ORDI-ROS J., MONEGAL FERRAN F., MARTINEZ N., CORTES-HERNANDEZ F. and VILARDELL-TARRES M.: IgA anticardiolipin antibodies-relation with other antiphospholipid antibodies and Clinical significance. Thromb. Haemost.,79: , LAKOS G., KISS E., REGECZY P., TARJÁN P., SOLTÉSZ P., ZEHER M., BODOLAY E., SZAKONY S.Z., SIPKA S. and SZEGEDI G.Y.: Isotype distribution and Clinical relevance of anti -ß2-glycoprotein I antibodies: Importance of IgA isotype. Clin. Exp. Immunol., 117: SHEN Y.M., LEE R., FRENKEL E. and SARODE R.: IgA antiphospholipid antibodies are an independent risk factor for thromboses. Lupus, 17: , BOIN F., FRANCHINI S., COLANTUONI E., ROSEN A., WIGLEY F.M. and CASCIOLA-ROSEN L.: Independent association of anti-ß2-glycoprotein I antibodies with macrovascular disease and mortality in scleroderma. Arthritis Rheum., 60: , FERRO G.V.D. and BASILI S.: Transient antiphospholipid antibodies positivity in with primary antiphospholipid. syndrome. Lupus, 5: , FANOPOULOS D., TEODORESCU M.R., VARGA J. and TEODORESCU M.: High frequency of abnormal levels of IgA anti-ß2-glycoprotein I antibodies in with systemic lupus erythematosus: Relationship with antiphospholipid syndrome. J. Rheumatol., 25: , PIERANGEL S.S. and RAND J.H.: Laboratory Heterogeneity of Antiphospholipid Antibodies in Handbook of Systemic Autoimmune Diseases; 1 st edition; ed. By series editor Asherson RA; volume 10: Antiphospholipid Syndrome in Systemic Autoimmune Diseases; ed. by: Cervera R., Reverter J.K. and Khamashta M.; Elsevier, Amsterdam- Boston-Heidelberg-London-New York-Oxford-Paris-San Diego-San Francisco-Singapore-Sydney-Tokyo, Chapter 3: 35, MAHLER M., NORMAN G.L., MERONI P.L. and KHA- MASHTA M.: Autoantibodies to domain 1 of ß2 glycoprotein 1: A promising candidate biomarker for risk management in antiphospholipid syndrome. Autoimmunity Reviews, 12: , BERTOLACCINI M.L., ATSUMI T., CONTRERAS A.E., KHAMASHTA M.A. and HUGHES G.R.V.: The value of IgA antiphospholipid testing for diagnosis of antiphospholipid (Hughes) syndrome in systemic lupus erythematosus. J. Rheumatol., 28: , CARMO-PEREIRA S., BERTOLACCINI M.L., ESCU- DERO-CONTRERAS A., KHAMASHTA M.A. and HUGHES G.R.V.: Value of IgA anticardiolipin and antiß2-glycoprotein I antibody testing in with pregnancy morbidity. Ann. Rheum. Dis., 62: , SAMARKOS M., DAVIES K.A., GORDON C. and LOIZOU S.: Clinical significance of IgA anticardiolipin and anti-ß2-gpi antibodies in with systemic lupus erythematosus and primary antiphospholipid syndrome. Clin. Rheumatol., 25: , MEHRANI T. and PETRI M.: Association of IgA Antiß2 Glycoprotein I with Clinical and Laboratory Manifestations of Systemic Lupus Erythematosus. J. Rheumatol., 38 (1): 64-68, MEHRANI T. and PETRI M.: IgM anti-ß2 glycoprotein I is protective against lupus nephritis and renal damage in systemic lupus erythematosus. J. Rheumatol., 38 (1): , PETRI M., ORABAI A.M., ALÁCRON G.S., GORDON C., MERRILL J.T., FORTIN P.R., BRUCE I.N., ISEN- BERG D., WALLACE D.J., NIVED O., STURFELT G., RAMSEY-GOLDMAN R., BAE S.C., HANLY J.G., SÁNCHEZ-GUERRERO J., CLARKE A., ARANOW C.,

7 Azza H. El-Awar, et al. 7 MANZI S., UROWITZ M., GLADMAN D., KALUNIAN K., COSTNER M., WERTH V.P., ZOMA A., BER- NATSKY S., RUIZ-IRASTORZA G., KHAMASHTA M.A., JACOBSEN S., BUYON J.P., MADDISON P., DOOLEY M.A., VAN VOLLENHOVEN R.F., GINZLER E., STOLL T., PESCHKEN C., JORIZZO J.L., CALLEN J.P., LIM S.S., FESSLER B.J., INANC M., KAMEN D.L., RAHMAN A., STEINS SON K., FRANKS A.G. Jr., SIGLER L., HAMEED S., FANG H., PHAM N., BREY R., WEISMAN M.H., MCGWIN G. Jr. and MAGDER L.S.: Derivation and validation of the Systemic Lupus International Collaborating Clinics (SLICC) Classification Criteria for systemic lupus erythematosus, Arthritis and Rheumatism, 64 (8): , TAN E.M., COHEN A.S., FRIES J.F., MASI A.T., McS- HANE D.J., ROTHFIELD N.F., SCHALLER J.G., TA- LAL N. and WINCHESTER R.J.: The 1982 revised criteria for the classification of systemic lupus erythematosus. Arthritis Rheum., 25: , HOCHBERG M.C.: Updating the American College of Rheumatology revised criteria for the classification of systemic lupus erythematosus. Arthritis Rheum., 40: 1725, WILSON W.A., CHARAVI A.E., KOIKE T., LOCKSHIN M.D., BRANCH D.W., PIETTE J.C., BREY R., DERK- SEN R., HARRIS E.N., HUGHES G.R., TRIPLETT D.A. and KHAMASHTA M.A.: International consensus statement on preliminary classification criteria for definite antiphospholipid syndrome: Report of an international workshop. Arthritis Rheum., 42: , BOMBARDIER C., GLADMAN D.D., UROWITZ M.B., CARON D. and CHANG C.H.: Derivation of the SLEDAI. A disease activity index for lupus. The Committee on Prognosis Studies in SLE. Arthritis Rheum., 35: , GLADMAN D., GINZLER E., GOLDSMITH C., FORTIN P., LIANG M., UROWITZ M., BACON P., BOMBAR- DIERI S., HANLY J., HAY E., ISENBERG D., JONES J., NIVED O., PETRI M., RICHTER M., SANCHEZ- GUERRERO J., SNAITH M., STURFELT G. and SYM- MONS D.: The development and initial validation of The Systemic Lupus International Collaborative Clinics/ American College of Rheumatology damage index for systemic lupus erythematosus. Arthritis and Rheumatism, 39 (3): , LEWIS S., KEIL L.B., BINDER W.L. and DEBARI V.A.: Standardized measurement of major immunoglobulin class (IgG, IgA, and IgM) antibodies to ß2 glycoprotein I in with antiphospholipid syndrome. J. Clin. Lab. Anal., 12: , GALEAZZI M., SEBASTIANI G.D., TINCANI A., PIETTE J.C., ALLEGRI F., MOROZZI G., BELLISAI F., SCORZA R., FERRARA G.B., CARCASSI C, FONT J., PASSIU G., SMOLEN J., PAPASTERIADES C., HOUSSIAU F., NEBRO A.F., RAMON GARRIDO E.D., JEDRYKA-GORAL A. and MARCOLONGO R.: HLA class II alleles associations of anticardiolipin and anti-ß2 GPI antibodies in a large series of European with systemic lupus erythematosus. Lupus, 9: 47-55, REBER G., BOEHLEN F. and De MOERLOOSE P.: Technical aspects in laboratory testing for antiphospholipid antibodies: Is standardization an impossible dream? Semin Thromb. Hemost., 34: , TINCANI A., FILIPPINI M., SCARSI M. and GALLI M. and MERONI P.L.: European attempts for the standardisation of the antiphospholipid antibodies. Lupus, 18: , WONG K.L., LIU H.W., HO K., CHAN K. and WONG R.: Anticardiolipin antibodies and lupus anticoagulant in Chinese with systemic lupus erythematosus. J. Rheumatol., 18: , MOLINA J.F., GUTIERREZ-URENA S., MOLINA J., URIBE O., RICHARDS S., De CEULAER C., GARCIA C., WILSON W.A., GHARAVI A.E. and ESPINOZA L.R.: Variability of anticardiolipin antibody isotype distribution in 3 geographic populations of with systemic lupus erythematosus. J. Rheumatol., 24: , CUCURULL E., GHARAVI A.E., DIRI E., MENDEZ E., KAPOOR D. and ESPINOZA L.R.: IgA anticardiolipin and anti-ß2-glycoprotein I are the most prevalent isotypes in African American with systemic lupus erythematosus. Am. J. Med. Sci., 318: 55-60, GRECO T.P., AMOS M.D., CONTI-KELLY A.M., NARANJO J.D. and IJDO J.W.: Testing for the antiphospholipid syndrome: Importance of IgA anti ß2 glycoprotein I. Lupus, 9: 33-41, MEIJIDE H., SCIASCIA S., SANNA G., KHAMASHTA M.A. and BERTOLACCINI M.L.: The Clinical relevance of IgA anticardiolipin and IgA anti-ß2 glycoprotein I antiphospholipid antibodies, A systematic review. Autoimmunity Reviews, 12: , LEE S.S., CHO M.L., JOO Y.S., KIM W.U., HONG Y.S., MIN J.K., LEE S.H., PARK S.H., CHO C.S. and KIM H.Y.: Isotypes of Anti-ß2-Glycoprotein I Antibodies: Association with Thrombosis in Patients with Systemic Lupus Erythematosus. J. Rheumatol., 28: , LEE R.M., BRANCH D.W. and SILVER R.M.: Immunoglobulin A anti -ß2-glycoprotein antibodies in women who experience unexplained recurrent spontaneous abortion and unexplained fetal death. Am. J. Obstet. Gynecol., 185: , IVERSON G.M., VON MUHLEN C.A., STAUB H.L., LASSEN A.J., BINDER W. and NORMAN G.L.: Patients with atherosclerotic syndrome, negative in anti-cardiolipin assays, make IgA autoantibodies that preferentially target domain 4 of ß2-GPI. J. Autoimmun., 27: , TSUTSUMI A., MATSUURA E., ICHIKAWA K., FUJISAKU A., MUKAI M. and KOIKE T.: IgA class anti ß2 glycoprotein I in with systemic lupus erythematosus. J. Rheumatol., 25: 74-78, BRUCE I.N., CLARK-SOLONINKA C.A., SPITZER K.A., GLADMAN D.D., UROWITZ M.B. and LASKIN C.A.: Prevalence of antibodies to ß2-glycoprotein I in systemic lupus erythematosus and their association with antiphospholipid antibody syndrome criteria: A single center study and literature review. J. Rheumatol., 27: , KUMAR S., PAPALARDO E., SUNKUREDDI P., NA- JAM S., GONZÁLEZ E.B. and PIERANGELI S.S.: Isolated elevation of IgA anti-ß2 glycoprotein I antibodies with manifestations of antiphospholipid syndrome: A case series of five. Lupus, 18: , 2009.

8 8 Relation of Immunoglobulin A Isotype 43- HANLY J.G., HONG C., SMITH S. and FISK J.D.: A prospective analysis of cognitive function and anticardiolipin antibodies in systemic lupus erythematosus. Arthritis Rheum., 42: , SEBASTIANI G.D., GALEAZZI M., TINCANI A., PI- ETTE J.C., FONT J., ALLEGRI F., MATHIEU A., SMOLEN J., De RAMON GARRIDO E., FERNANDEZ- NEBRO A., JEDRYKA-GORAL A., PAPASTERIADES C., MOROZZI G., BELLISAI F., De PITA O. and MAR- COLONGO R.: Anticardiolipin and anti-ß2gpi antibodies in a large series of European with systemic lupus erythematosus. Prevalence and Clinical associations. European Concerted Action on the Immunogenetics of SLE. Scand J. Rheumatol., 28: , MANKAI A., ACHOUR A., THABET Y., MANOUBIA W., SAKLY W. and GHEDIRA I.: Anti-cardiolipin and anti-ß2-glycoprotein I antibodies in celiac disease. Pathologie. Biologie., 60 (5): , GABETA S., NORMAN G.L., GATSELIS N., LIASKOS C., PAPAMICHALIS P.A., GARAGOUNIS A., ZACHOU K., RIGOPOULOU E.I. and DALEKOS G.N.: IgA antiß2gpi antibodies in with autoimmune liver diseases. J. Clin. Immunol., 28: , CERVERA R., CONTI F., DORIA A., IACCARINO L. and VALESINI G.: Does seronegative antiphospholipid syndrome really exist? Autoimmun. Rev., 11: , VIARD J.P., AMOURA Z. and BACH J.F.: Association of anti-ß2-glycoprotein I antibodies with lupus-type circulating anticoagulant and thrombosis in systemic lupus erythematosus. Am. J. Med., 93: , BALESTRIERI G., TINCANI A., SPATOLA L., ALLE- GRI F., PRATI E., CATTANEO R., VALESINI G., DEL PAPA N. and MERONI P.: Anti-ß2-glycoprotein I anti- bodies: A marker of antiphospholipid syndrome? Lupus, 4: , CABIEDES J., CABRAL A.R. and ALARCON-SEGOVIA D.: Clinical manifestations of the antiphospholipid syndrome in with systemic lupus erythematosus associate more strongly with anti-ß2-glycoprotein-i than with antiphospholipid antibodies. J. Rheumatol., 22: , MARTINUZZO M.E., FORASTIERO R.R. and CAR- RERAS L.O.: Anti-ß2-glycoprotein I antibodies: Detection and association with thrombosis. Br. J.Haematol., 89: , McNALLY T., MACKIE I.J., MACHIN S.J. and ISEN- BERG D.A.: Increased levels of ß2 glycoprotein-i antigen and ß2 glycoprotein-i binding antibodies are associated with a history of thromboembolic complications in with SLE and primary antiphospholipid syndrome. Br. J. Rheumatol., 34: , SHEN Y.M., LEE R., FRENKEL E. and SARODE R.: IgA antiphospholipid antibodies are an independent risk factor for thromboses. Lupus, 17: , LOIZOU S., CIFINER C., WEETMAN A.P. & WALPORT M.J.: Immunoglobulin class and IgG subclass distribution of anticardiolipin antibodies in with systemic lupus erythematosus and associated disorders. Clin. Exp. Imunol., 90: , ESCALANTE A., BREY R.L., MITCHELL B.D. Jr. and DREINER U.: Accuracy of anticardiolipin antibodies in identifying a history of thrombosis among with systemic lupus erythematosus. Am. J. Med., 98: , PETRI M.: Epidemiology of Antiphospholipid Syndrome. In Hughes Syndrome textbook; 2 nd edition; ed. by Khamashta M.A.; Springer-Verlag London Limited, Section 1; Chapter 3: 22-28, 2006.