Quantitative detection of red blood cell antibody-mediated complement activation

Abstract

Objective To construct an in-vitro model of erythrocyte antibody-mediated complement activation, and establish quantitative detection methods based on flow cytometry and spectrophotometry, so as to explore the correlation of anti-body titers and complement activation speed, and provide a methodological basis for studying the adverse transfusion reactions of anti-body mediated complement hemolysis. Methods Mouse monoclonal antibody that recognized human C3b and fluorescent secondary antibody were used to label C3b fragments on erythrocytes, and the deposition of C3b fragments after complement activation was detected by flow cytometry. The absorbance at 540 nm of the supernatant in the complement activation reaction system was measured by spectrophotometry as the amount of hemoglobin released was related to the absorbance. Results The complement activation system was constructed according to the ratio of 3% red blood cell suspension (mixed for 6 people) 1∶anti-Tja 1∶complement 2. The repeatability was good (P value>0.05) as different red blood cell mixtures had been used to repeat the detection reaction system. When using 32×, 64× and 128× dilutions of anti-Tja mediated complement activation, the deposition of C3b fragments has been detected by flow cytometry at 30 s, 1 min and 2 min, respectively, and MFI peaked at 5 min, 10 min and 30 min, respectively. No obvious hemolysis has been observed within 1.5 h. Conclusion In vitro model of anti-Tja-mediated complement activation demonstrates the speed of complement activation is related to the concentration of antibody. At a certain antibody concentration, the speed of complement activation has been slowed down, and no obvious hemolysis observed.

Keywords

• complement activation
• red blood cell antibody
• flow cytometry
• spectrophotometry