Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA.
University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA.
Lupus Sci Med. 2020 Apr;7(1). doi: 10.1136/lupus-2019-000377.
To evaluate the association between lupus severity and cell-bound complement activation products (CB-CAPs) or low complement proteins C3 and C4.
All subjects (n=495) fulfilled the American College of Rheumatology (ACR) classification criteria for SLE. Abnormal CB-CAPs (erythrocyte-bound C4d or B-lymphocyte-bound C4d levels >99th percentile of healthy) and complement proteins C3 and C4 were determined using flow cytometry and turbidimetry, respectively. Lupus severity was estimated using the Lupus Severity Index (LSI). Statistical analysis consisted of multivariable linear regression and groups comparisons.
Abnormal CB-CAPs were more prevalent than low complement values irrespective of LSI levels (62% vs 38%, respectively, p<0.0001). LSI was low (median 5.44, IQR: 4.77-6.93) in patients with no complement abnormality, intermediate in patients with abnormal CB-CAPs (median 6.09, IQR: 5.31-8.20) and high in the group presenting with both abnormal CB-CAPs and low C3 and/or C4 (median 7.85, IQR: 5.51-8.37). Odds of immunosuppressant use was higher in subjects with LSI ≥5.95 compared with subjects with LSI <5.95 (1.60 vs 0.53, p<0.0001 for both). Multivariable regression analysis revealed that higher LSI scores associated with abnormal CB-CAPs-but not low C3/C4-after adjusting for younger age, race and longer disease duration (p=0.0001), which were also independent predictors of disease severity (global R=0.145).
Abnormalities in complement activation as measured by CB-CAPs are associated with increased LSI.
评估狼疮严重程度与细胞结合补体激活产物（CB-CAP）或低补体蛋白 C3 和 C4 之间的关系。
所有受试者（n=495）均符合美国风湿病学会（ACR）SLE 分类标准。采用流式细胞术和比浊法分别测定异常 CB-CAP（红细胞结合 C4d 或 B 淋巴细胞结合 C4d 水平>99%健康人群的第 99 百分位数）和补体蛋白 C3 和 C4。使用狼疮严重程度指数（LSI）评估狼疮严重程度。统计分析包括多变量线性回归和组间比较。
异常 CB-CAP 的发生率高于低补体值，无论 LSI 水平如何（分别为 62%和 38%，p<0.0001）。无补体异常患者的 LSI 较低（中位数 5.44，IQR：4.77-6.93），CB-CAP 异常患者的 LSI 为中等（中位数 6.09，IQR：5.31-8.20），同时存在 CB-CAP 异常和低 C3 和/或 C4 的患者的 LSI 较高（中位数 7.85，IQR：5.51-8.37）。LSI≥5.95 的患者与 LSI<5.95 的患者相比，使用免疫抑制剂的可能性更高（1.60 比 0.53，p<0.0001）。多变量回归分析显示，在校正年龄、种族和疾病持续时间更长后，更高的 LSI 评分与异常 CB-CAP 相关，但与低 C3/C4 无关（p=0.0001），且这也是疾病严重程度的独立预测因素（整体 R=0.145）。
CB-CAP 测定的补体激活异常与 LSI 升高相关。
