INTRODUCTION Systemic lupus erythematosus (SLE) is a multi-systemic colla- gen vascular disease of unknown cause, probably due to a regula- tion disorder in the immune system.1 Different groups have repor- ted prevalences of 40 to 565 per 100,000 women.1 This is about ten times the prevalence in men. With more accurate diagnostic techniques and increasing experience with the use of immuno- suppressive agents, the prognosis is improving. Renal and central nervous system involvement are factors still adversely affecting the prognosis.2-4 Lupus nephritis is defined as renal involvement with clinical and laboratory findings such as hypertension, nephritic or nephro- tic syndrome, chronic renal failure or proteinuria, and hematuria with no other cause in patients with SLE.5 However, it must be kept in mind that in patients with SLE renal involvement may be present with no apparent serum or urine findings.1,6 Therefore, a marker to detect asymptomatic as well symptomatic lupus nephri- tis is being sought. Anti-C1q antibody (anti-C1q) presence has been proposed as a marker of lupus nephritis.7 C1q is a part of the complement system. It has a role in the binding and clearing of the immune complexes that are circulating or bound to the tissues. It has been reported that C1q has a role in the clearing of apoptotic cell material even in the absence of antibodies.8 In rats with C1q deficiency that show a high risk of renal involvement with SLE development, many apoptotic bodies in the glomeruli are shown, which supports the idea that apoptosis may have a role in nephritis development.9 The term antiphospholipid syndrome (APS) was first defined by Hughes as the hypercoagulability syndrome in the presence of antiphospholipid antibodies.10 Antibodies such as anti-b2- glycoprotein 1 antibodies (anti-b2GP1), low titer anticardiolipin IgG, anticardiolipin IgM and anticardiolipin IgA antibodies (aCL IgG, aCL IgM, aCL IgA, respectively), and other antiphospholipid antibodies are commonly present in patients with APS. It was de- monstrated that in patients with APS antiphospholipid antibodies that can bind cardiolipin require a factor called b2-glycoprotein 1, and it is suggested that these groups of antibodies may be impor- tant in predicting thrombotic events. b2-glycoprotein I is a glycoprotein that is normally present in the plasma, but its physiologic significance is unknown. In vit- ro, it is shown to inhibit prothrombinase activity, contact pathway activation, ADP induced thrombocyte aggregation, and factor Xa formation by thrombocytes. Therefore, it is a weak, natural anticoagulant.11,12 In SLE, b2-glycoprotein I has autoantigenic properties for both B and T lymphocytes.13,14 In a multi-center study in Europe, medium-high titers of aCL IgG and anti-b2GP1 were found to be associated with thrombosis, AN ANALYSIS OF THE RELATIONSHIP BETWEEN DIFFERENT AUTOANTIBODIES AND CLINICAL FINDINGS IN A GROUP OF TURKISH PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS N. Defne ALTINTAŞ 1 , A. Olcay TIRYAKI 2 , Hüseyin TUTKAK 2 , Nurşen DÜZGÜN 2 ABSTRACT Purpose: To study the prevalence of different anticardiolipin antibody isotypes (aCLs), anti-C1q antibodies (anti-C1q), and anti-b2-glycoprotein 1 IgG antibo- dies (anti-b2GP1 IgG) in a group of Turkish SLE patients and their association with lupus nephritis and extra-renal involvement. Materials and Methods: SLE patients who were evaluated in Ankara Univer- sity Faculty of Medicine, Department of Clinical Immunology and Rheuma- tology between May 2001 and May 2002 were included in the study, unless they were also hemodialysis patients. Disease duration, medications, organ involvement, disease complications and follow-up laboratory results were re- corded. Disease activity was evaluated with SLEDAI; a score of ≥ 4 indicated active disease. Antibody titers were determined using the enzyme immunoas- say method. Results: A total of 62 patients (51 women, 11 men) were included. The mean age was 37. Average duration of illness was 104 months. Of the patients, 55% had a SLEDAI score of ≥ 4. Renal involvement was present in 76%, with active nephritis in 49%. Thrombosis was present in 11%, 16% had obstetric complications, 37% had neurologic findings, 26% had thrombocytopenia, and 45% had Raynaud’s phenomenon. None of the antibodies were related to re- nal involvement. Patients with SLEDAI ≥ 4 had significantly increased total aCL positivity (p<0.05). There was no relation between disease duration and antibody positivity. Anti-b2GP1 IgG and aCL IgG were significantly related to thrombosis (p<0.05). The negative predictive value of aCL for thrombosis was high, 94%. A significant association between thrombocytopenia and aCL IgG positivity was observed (p=0.026). Anti-b2GP1 IgG positivity showed a significant correlation with all aCL isotypes. None of the antibodies had a significant relationship with obstetric complications, neurologic findings, or Raynaud’s phenomenon. Conclusions: The findings that aCL IgG positivity was closely associated with thrombotic events and thrombocytopenia, and anti-b2GP1 IgG was closely as- sociated with aCL levels and thrombosis were in accordance with the general literature. No relation between anti-C1q and renal involvement, renal flare, or proliferative nephritis was demonstrated in this group of Turkish patients. Key Words: Anti-C1q, Anticardiolipin Antibodies, Anti-b2-glycoprotein 1, Systemic Lupus Erythematosus, Nephritis. SISTEMIK LUPUS ERITEMATOZUSLU BIR GRUP TÜRK HASTADA FARKLI OTOANTIKORLAR VE KLINIK BULGULAR ARASINDAKI ILIŞKININ INCELENMESI ÖZ Amaç: Sistemik lupus eritematozuslu (SLE) bir grup Türk hastada farklı an- tikardiyolipin antikor izotiplerinin (aCL), anti-C1q antikor (anti-Cq1) ve anti- beta2-glikoprotein 1 IgG (anti-b2GP1 IgG) antikor sıklığının ve lupus nefriti ve ekstra-renal tutulum ile ilişkisinin incelenmesi. Hastalar ve Yöntemler: Ankara Üniversitesi Tıp Fakültesi, Klinik İmmüno- loji ve Romatoloji departmanında Mayıs 2001 – Mayıs 2002 tarihleri arasında değerlendirilen SLE’li hastalar çalışmaya dahil edildi. Hemodiyaliz ihtiyacı olanlar çalışma dışında tutuldu. Hastalık süreleri, ilaçları, organ tutulumları, hastalık komplikasyonları ve laboratuvar sonuçları kaydedildi. Hastalık aktivi- tesi SLEDAI ile değerlendirildi; skorun ≥ 4 olması aktif hastalık olarak kabul edildi. Antikor titreleri enzim immunoassay yöntemiyle değerlendirildi. Bulgular: Toplam 62 hasta (51 kadın, 11 erkek) çalışmaya alındı. Ortalama yaş 37; ortalama hastalık süresi 104 aydı. Hastaların %55’inin SLEDAI sko- ru ≥ 4’tü. Renal tutulum %76’sında, aktif nefrit %49’unda saptandı. Tromboz %11’inde, obstetrik komplikasyonlar %16’sında, nörolojik komplikasyonlar %37’sinde, trombositopeni %26’sında, Raynaud fenomeni %45’inde mevcuttu. Antikorların hiçbiri renal tutulum ile ilişkili bulunmadı. SLEDAI ≥ 4 olanlarda toplam aCL pozitifliği anlamlı olarak yüksekti (p<0.05). Hastalık süresiyle an- tikor varlığı arasında ilişki yoktu. Anti-b2GP1 IgG ve aCL IgG anlamlı olarak trombozla ilişkili bulundular (p<0.05). Tromboz için aCL’nin negatif predik- tif değeri yüksek bulundu, 94%. Trombositopeni ve aCL IgG varlığı arasında anlamlı ilişki vardı (p=0.026). Anti-b2GP1 IgG varlığı tüm aCL izotipleriyle anlamlı korelasyon göstermekteydi. Antikorların hiçbiri obstetrik komplikas- yonlar, nörolojik bulgular ya da Raynaud fenomeni ile ilişkili değildi. Sonuç: aCL IgG varlığının trombotik olaylar ve trombositopeniyle ilişkili bulunması; anti-b2GP1 IgG’in aCL düzeyleri ve trombozla ilişkili bulunması literatürle uyumluydu. Ancak Anti-C1q ile renal tutulum, aktif renal hastalık ve proliferatif nefrit arasında hiçbir ilişki gösterilemedi. Anahtar Kelimeler: Anti-C1q, Antikardiyolipin Antikorları, Anti-beta 2-glikoprotein 1, Sistemik Lupus Eritematozus, Nefrit. 1 Hacettepe Üniversitesi Tıp Fakültesi İç Hastalıkları Anabilim Dalı Ankara 2 Ankara Üniversitesi Tıp Fakültesi İç Hastalıkları Anabilim Dalı Klinik İmmünoloji ve Romatoloji Bilim Dalı Ankara ARAŞTIRMA - RESEARCH ARTICLE 2008: Cilt 19: Sayı 3: 126-132 Gazi Tıp Dergisi / Gazi Medical Journal