Anti-SmD抗體和Anti-Sm抗體用於全身性紅班狼瘡的診斷

Anti-SmD and anti-Sm antibodies in the diagnosis of systemic lupus erythematosus

背景：anti-Sm抗體是全身性紅斑狼瘡的專一性抗體之一，也是美國風濕病學會的診斷標準之一。但此在臨床測量的準確性隨著不同的檢測方式和在不同族群之間有不同的陽性值。本篇研究目的在於比較使用更純化的SmD3多肽做為anti-Sm抗體的目標（亦稱anti-SmD），是否能提升診斷全身性紅斑狼瘡的檢測率。方法：使用螢光酵素免疫檢驗，比較全身性紅斑狼瘡、類風濕性關節炎、和正常健康者的anti-Sm和anti-SmD抗體檢出率，並以接受者操作特性（ROC）曲線重獲新的臨界值。結果：本研究總共收集了全身性紅斑狼瘡213位，類風濕性關節炎75位，正常健康人108位。舊有anti-Sm抗體檢測率分別為：全身性紅斑狼瘡5.63%，類風濕性關節炎和健康組皆為0%。新的anti-SmD陽性率則為：全身性紅斑狼瘡21.13%，類風濕性關節炎0%，健康組3.85%。anti-Sm和anti-SmD檢驗的敏感度分別為5.63%和21.13%。若以ROC曲線分析所得的臨界值，則在本研究族群中可提升新的anti-SmD檢驗工具的敏感度至27.7%。結論：使用純化的SmD3多肽做為anti-Sm抗體的免疫反應目標，可大幅提昇該檢測的診斷能力。以ROC建立的新臨界值，本研究中全身性紅班狼瘡的anti-SmD抗體盛行率為27.7%。

Backgrounds: Anti-Sm antibody is specific to systemic lupus erythematosus (SLE) and is one of the American College of Rheumatology’s criteria for SLE. However, the clinical accuracy varies according to different detection systems. This study is to investigate if a new test kit with synthetic anti-SmD3 peptides has a better diagnostic performance. Methods: We used a fluorescent enzyme immunoassay to determine anti-Sm and anti-SmD levels in a SLE group, a rheumatic disease control (rheumatoid arthritis, RA) and a healthy control (HC) group. Receiver operating characteristic curves were constructed and the cut-off value established was able to increase sensitivity of anti-SmD measurement. Results: In total, 213 SLEs, 75 RAs and 108 HCs were studied. Of these, 5.63% of SLEs, 0% of RAs and 0% of HCs were positive for anti-Sm while anti-SmD was positive in 21.13%, 0% and 3.85% of SLE, RA and HC respectively. The sensitivity of anti-Sm and anti-SmD test kit was 5.63% and 21.13% respectively. With the cut-off value analyzed by receiver operating characteristic (ROC) curve, sensitivity was increased to 27.7%. Conclusions: Anti-SmD antibodies have high specificity for SLE and the test kit using SmD3 antigen has better diagnostic performance. In this study population, we identified 27.7% of SLE patients as being was positive for anti-SmD antibodies.