State Key Laboratory of Experimental Hematology, Institute of Hematology & Blood Diseases Hospital, National Clinical Research Center for Blood Diseases, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin, China.
Int J Lab Hematol. 2021 Oct;43(5):1154-1158. doi: 10.1111/ijlh.13469. Epub 2021 Jan 18.
Abnormally activated complement system induces erythrolysis in a part of autoimmune hemolytic anemia (AIHA) patients. However, the alterations in serum complement levels in these patients are seldom reported. In this study, we aimed to evaluate the serum complement features of AIHA patients according to different clinical and laboratory characteristics and to find relationships between complement levels and hemolysis-associated laboratory indexes.
A retrospective analysis of 146 AIHA patients was performed, and serum complement C3 and C4 levels were compared between control subjects and AIHA patients with different subtypes. Correlations of serum C3/C4 levels with titers of cold agglutinin test (CAT), direct antiglobulin test (DAT), and serological indexes were assessed. Spearman correlation analysis was performed to analyze the relationship between serum complement levels and other laboratory indexes.
Autoimmune hemolytic anemia patients showed reduced serum C3 levels, while serum C4 levels tended to be lower in DAT-positive AIHA patients but not in DAT-negative AIHA patients. Patients with warm AIHA secondary to connective tissue diseases and cold agglutinin disease/cold agglutinin syndrome had the lowest serum C3/C4 levels. Serum C4 levels were negatively correlated with CAT (P = .004) and DAT (anti-C3d) (P = .007) titers. In patients with positive CAT and/or DAT (anti-C3d) but negative DAT (anti-IgG), serum C3/C4 levels were negatively correlated with indirect bilirubin (P = .017 and =.026, respectively).
The study findings may be helpful in not only unraveling the mechanism underlying hemolysis in AIHA but also diagnosing AIHA and selecting targeted treatment strategies.
异常激活的补体系统可导致部分自身免疫性溶血性贫血（AIHA）患者发生红细胞溶解。然而，这些患者的血清补体水平变化很少有报道。本研究旨在根据不同的临床和实验室特征评估 AIHA 患者的血清补体特征，并寻找补体水平与溶血相关实验室指标之间的关系。
对 146 例 AIHA 患者进行回顾性分析，比较对照组和不同亚型 AIHA 患者的血清补体 C3 和 C4 水平。评估血清 C3/C4 水平与冷凝集素试验（CAT）、直接抗球蛋白试验（DAT）和血清学指标的相关性。采用 Spearman 相关分析评估血清补体水平与其他实验室指标的关系。
AIHA 患者血清 C3 水平降低，而 DAT 阳性 AIHA 患者血清 C4 水平趋于降低，但 DAT 阴性 AIHA 患者则不然。继发于结缔组织疾病和冷凝集素病/冷凝集素综合征的温抗体型 AIHA 患者的血清 C3/C4 水平最低。血清 C4 水平与 CAT（P =.004）和 DAT（抗-C3d）（P =.007）滴度呈负相关。在 CAT 和/或 DAT（抗-C3d）阳性但 DAT（抗-IgG）阴性的患者中，血清 C3/C4 水平与间接胆红素呈负相关（P =.017 和 P =.026）。
这些研究结果不仅有助于阐明 AIHA 溶血的机制，还有助于诊断 AIHA 和选择靶向治疗策略。
