Anti-dsDNA antikorlarının saptanmasında üç ELISA yönteminin CLIF testiyle karşılaştırılması

Abstract

Amaç: Sistemik lupus eritematozus SLE hücre çekirdeğindeki antijenlere karşı antikorların oluşturduğu otoimmün bir hastalıktır. Amerikan Romatoloji Derneği ACR kriterlerine göre SLE tanısında kullanılan immünolojik parametreler anti nükleer antikor ANA ve anti-dsDNA otoantikorlarıdır. Bu çalışmada anti-dsDNA antikorların saptanmasında, CLIF yöntemi referans yöntem kabul edilerek, üç farklı ELISA kitinin özgüllüğünün araştırılması amaçlanmıştır. Yöntemler: Çalışmaya 1 Mayıs – 31 Temmuz 2013 tarihleri arasında hastanemiz mikrobiyoloji laboratuvarına gönderilen klinik olarak SLE tanısı almış olan 81 hastanın serum örnekleri dahil edilmiştir. Bu serumlarda ANA varlığı öncelikle immünfloresan antikor IFA yöntemiyle araştırılmıştır. Pozitif serum örnekleri -80 OC’de prospektif analiz için saklanmış ve aynı gün dört farklı anti-dsDNA testi ile çalışılmıştır. Bu testler; üç adet anti-dsDNA ELISA kiti; CHORUS dsDNA-G DIESSE Diagnostica Senese, İtalya , Anti-dsDNA-Ncx ELISA IgG EUROİMMUN, Almanya , QUANTA Lite dsDNA SC ELISA INOVA Diagnostics, Kaliforniya ve CLIF testi Crithidia luciliae anti-dsDNA, EUROIMMUN, Almanya idi. Bulgular: Hastaların IFA yöntemi ile ANA paternleri; %35,8 homojen patern, %22,2 homojen+diğer patern, %24,7 granüler patern, %8,7 granüler + diğer paternler, %7,4 nükleolar patern ve %1,2 sentromer patern olarak belirlenmiştir. Bu sonuçlara göre SLE hastalarında en sık rastlanan ANA paterni homojen patern olmuştur. Çalışılan 81 serum örneğinin anti-dsDNA pozitiflikleri; CLIF yöntemi ile 22 %27 , INOVA ile 46 %56 , EUROIMMUN ile 34 %41 , CHORUS ile 50 %61 saptanmıştır. CLIF referans yöntem kabul edildiğinde ELISA kitlerinin özgüllükleri ve pozitif prediktif değerleri PPD sırasıyla; CHORUS ile %50, %42; INOVA ile %54, %41; EUROIMMUN ile %71, %50’dir.Sonuç: ANA pozitif olgularda incelenen yöntemler içinde Anti-dsDNA-Ncx ELISA IgG yöntemi diğer yöntemlere göre daha yüksek özgüllük ve PPD’e sahiptir. Bu çalışmanın CLIF yöntemi kullanılmadığında seçilecek ELISA yöntemi açısından laboratuvarlara yol gösterici olacağı düşünülmektedir

Keywords

• Sistemik lupus eritematozus, SLE, anti-dsDNA, CLIF, ELISA

Comparison of three ELISA methods with CLIF test for detection of Anti-dsDNA antibody

Abstract

Objective: Systemic lupus erythematosus SLE is an autoimmune disease caused by antibodies which produced against antigens commonly on cell nuclei. According to the criteria of American College of Rheumatology ACR , the immunological parameters which are used for diagnosis of SLE, are anti- nuclear antibodies ANA and anti- dsDNA autoantibodies. In this study it is aimed to investigate the specifity of three different ELISA tests by comparing with CLIF test, as a reference method, for the determination of anti-dsDNA antibodies. Methods: Sera of 81 patients who were diagnosed as SLE and sent to the Microbiology Department of our hospital between 1 May - 31 July 2013, were included in the study. In these sera, ANA positivity was firstly investigated by immunofluorescence antibody test IFA . Positive sera were stored at -80 OC for prospective analysis and processed with four different anti-dsDNA assays at the same day. These assays were three antidsDNA ELISA kits including; CHORUS dsDNA-G DIESSE Diagnostica Senese, Italy , anti-dsDNA-Ncx ELISA IgG EUROIMMUN, Germany, California , QUANTA Lite dsDNA SC ELISA INOVA Diagnostics and CLIF test Crithidia luciliae anti-dsDNA, EUROIMMUN, Germany . Results: ANA patterns of patients defined by IFA were determined as; 35.8% homogeneous pattern, 22.2% homogeneous and other patterns, 24.7% granular pattern, 8.7% granular and other patterns, 7.4% nucleolar pattern and 1.2% centromere pattern. According to these results, most common ANA pattern in SLE patients was found as homogeneous pattern. AntidsDNA positiveness of 81 sera samples were 22 27% with CLIF test, 46 56% with INOVA, 34 41% with EUROIMMUN and 50 61% with CHORUS. When CLIF test was considered as reference method, specificity, and positive predictive value PPV of ELISA kits were respectively; 50%, 42% for CHORUS; 54%, 41%for INOVA and 71%, 50% for EUROIMMUN. Conclusion: Anti-ds DNA-NcX IgG ELISA method had higher specifity and PPV than other tested methods in ANA positive cases. It is thought that this study may guide the laboratories to choose ELISA method in lack of CLIF method.

Keywords

• Systemic lupus eriythematozus, SLE, anti-dsDNA, CLIF, ELISA

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