使用紅血球上C4d對紅血球上第一型補體受器之比值來預測並評估狼瘡活動性

Predictive value of erythrocyte-bound C4d to erythrocyte-complement receptor type 1 ratio in lupus disease activity

目的：與紅血球結合的C4d（E-C4d）與第一型補體受器（E-CR1）都是新一代的生物標記，可以用來診斷狼瘡或追蹤其疾病活動性，這個研究的目的主要針對使用一種新的第一型補體受器之抗體（CR1-2B11）來測定E-C4d對CR1的比值（E-C4d/E-CR1 ratio），用以評估狼瘡病人疾病活動性與此比值之臨床相關性。方法：此研究納入六個全身性紅斑狼瘡的病人，每個人的週邊血液用流式細胞儀來分析其E-C4d與E-CR1的數值，並換算出其比值。結果：全身性紅斑狼瘡的病人在經免疫抑制劑治療後，平均的E-C4d/E-CR1 ratio有明顯的下降（12.93 ± 1.9 vs. 3.52 ± 0.9, p<0.05），其中三個全身性紅斑狼瘡的病人在經適當治療並穩定其狼瘡活動性後，病人的E-C4d/E-CR1 ratio數值皆有大幅下降（19.23 to 1.01, 5.47 to 1.25, and 13.16 to 2.40）。結論：相對應的E-C4d與E-CR1的數值變化在全身性紅斑狼瘡的病人是相當重要，E-C4d/E-CR1 ratio可以當作一個很好的生物標記用來預測狼瘡活動性也可以幫助對狼瘡病人治療之評估。

Objective: Erythrocyte-bound C4d (E-C4d) and erythrocyte-complement receptor type 1 (E-CR1) are both novel biomarkers to diagnose systemic lupus erythematosus (SLE) and to monitor disease activity. This study aimed at determining the ratio of E-C4d to E-CR1 (E-C4d/E-CR1) using mouse monoclonal antibody CR1-2B11 and correlating the clinical association of this ratio with disease activity of SLE. Methods: This study included 6 SLE patients, and their blood samples were collected before and after immunosuppressive therapy. E-C4d and E-CR1 levels were measured using indirect immunofluorescence and flow cytometry on the same day as the blood drawing, and the E-C4d/E-CR1 ratios were calculated from the values obtained. Results: The mean of the E-C4d/E-CR1 ratio was significantly decreased in SLE patients after immunosuppressive therapy (12.93 ± 1.9 vs. 3.52 ± 0.9, p<0.05). Three of the 6 SLE patients showed decreased ratios when their active disease stabilized after adequate treatment respectively (19.23 to 1.01, 5.47 to 1.25, and 13.16 to 2.40). Conclusion: The reciprocal change in E-C4d and E-CR1 levels is important in SLE patients. The E-C4d/E-CR1 ratio assessed with CR1-2B11 could be a good biomarker to predict disease activity and may be helpful in formulating a therapeutic strategy in SLE.