Report on the Effects Lipemic Specimen in Anti-ds DNA Antibody Test

Anti-ds DNA 항체 검사 시 Lipemic 검체의 영향에 관한 보고

Purpose: SLE (systemic lupus erythematosus) is an inflammatory autoimmune disease, characterized by various autoantibody. The detection of Anti double-stranded DNA (Anti-ds DNA) is important in the diagnostics of SLE, and include the American College of Rheumatology (ACR) diagnostic criteria for SLE. Also SLE disease activity and correlativity with the level Anti-ds DNA antibody have been reported and Anti-ds DNA antibody quantitative test is very useful for tracing before and after SLE treatment. When These Anti-ds DNA antibody test (Farr assay: $^{125}I$ labeled ds-DNA and bound Anti-ds DNA antibodies complex in serum is precipitated by ammonium sulfate and used to centrifugation, measured it) inhaled supernatant after centrifugation, a lipemic specimen does not facilitate the formation of precipitate and also occurs situation was inhaled with precipitate. To solve these problems, The Influence of the degree of lipemic specimen was evaluated. Materials and Methods: September 2012 to February 2013, We selected lipemic samples (n=81) of specimen commissioned by Anti-ds DNA antibody test. Lipemic samples were done pre-treatment (high-speed centrifugation: 14,000 rpm 5 mins) used a micro-centrifuge (Eppendorf Model 5415D). At the same time lipemic specimen and pre-treatment samples were performed Anti-ds DNA antibody test (Anti-ds DNA kit, Trinity Biotech, Ireland). Statistical analysis were analyzed Pearson's correlation coefficients and regression and paired t-test, and Difference (%). Results: Experimental group 1 (Lipemic Specimen Anti-ds DNA Ab concentration ${\leq}7IU/mL$) at y=0.368X+4.732, $R^2=0.023$, Pearson's correlation coefficient was 0.154, paired t-test (P=0.003), Difference (%) mean 65.7 and showed a statistically significant difference. Experimental group 2 (Lipemic Specimen Anti-ds DNA Ab concentration ${\geq}8IU/mL$) at y=0.983X+0.298, $R^2=0.994$, Pearson's correlation coefficient showed 0.997, paired t-test (P=0.181), Difference (%) mean -5.53 made no statistically significant difference. Conclusion: Lipemic sample of low Anti-ds DNA Ab concentration (2.5-7 IU/mL) and the result is obtained pre-treatment (high-speed centrifugation: 14,000 rpm 5 mins) were made a significant difference statistically. Anti-ds DNA is one of the primary auto-antibodies present in patients with SLE, and remain an important diagnostic test for SLE. Therefore, we recommend preprocessing (high-speed centrifugation: 14,000 rpm 5 mins) in order to exclude the influence of lipemic specimen.

Anti double-stranded DNA (Anti-ds DNA)항체의 검출은 SLE의 진단에 중요하며 American College of Rheumatologists의 SLE 진단기준에 포함되어 있다. 또한 SLE 질병의 활성도와 Anti-ds DNA 항체 수준의 상관성이 보고되어 있으며 Anti-ds DNA 항체 정량검사는 SLE의 치료 전, 후 추적에 매우 유용하다. Anti-ds DNA 항체의 검출을 위한 검사 방법으로 방사면역측정법(radioimmunoassay, RIA)을 이용한 Farr assay, Crithidia luciliae를 이용한 면역형광 측정법(immunofluorescence Test, CLIFT), 효소면역측정법(enzyme-linked immunosorbent assay, ELISA), 화학발광면역 측정법(chemiluminescence immunoassay, CLIA)이 있다. 본원에서 방사면역측정법(radioimmunoassay, RIA)으로 Anti-ds DNA 항체 검사 과정에서 lipemic한 검체의 경우 침전물의 형성이 원활하지 않거나 침전물도 같이 흡입되는 상황이 발생 하였고, 이러한 문제점을 해결하기 위해 lipemic 검체가 분석 결과에 미치는 영향 정도를 평가하였다. 2012년 9월부터 2013년 2월까지 Anti-ds DNA 항체 검사가 의뢰된 검체 중 lipemic한 검체(n=81)를 선택하여 마이크로 원심분리기로 전처리(고속 원심분리: 14,000 rpm 5 mins)한 후 동시에 Anti-ds DNA 항체 검사(Anti-ds DNA kit, Trinity Biotech, Ireland)를 시행하였다. 실험군 1 (lipemic 검체의 Anti-ds DNA 항체 농도 ${\leq}7IU/mL$)에서 y=0.3636x+4.7322, $R^2=0.0238$, Pearson 상관계수는 0.154, paired t-test (P=0.003), Difference (%) mean 65.7의 결과를 얻었으며 통계적으로 유의한 차이를 보였다. 그러나 실험군 2 (lipemic 검체의 Anti-ds DNA 항체 농도 ${\geq}8IU/mL$)에서 y=0.9837x+0.2982, $R^2=0.994$, Pearson 상관계수는 0.997, paired t-test (P=0.181), Difference (%) mean -5.53을 보였고 통계적으로 유의한 차이가 없음을 확인할 수 있었다. 임상에서 SLE (systemic lupus erythematosus)의 진단에 중요한 역할을 하는 Anti-ds DNA 항체 검사는 lipemic 검체의 영향을 배제하기 위해서 반드시 전처리(고속 원심분리: 14,000 rpm 5 mins) 과정을 통해 혈청 내 지질 성분을 제거한 후 검사를 시행하여야 한다.