Related Experiment Video
Updated: Aug 14, 2026

Methods for Quantitative Detection of Antibody-induced Complement Activation on Red Blood Cells
Published on: January 29, 2014
Human erythrocytes inhibit complement-mediated solubilization of immune complexes
B L Dorval1, F G Cosio, D J Birmingham
1Department of Internal Medicine, Ohio State University College of Medicine, Columbus 43210-1228.
Incubation of precipitable immune complexes (IC) with fresh human serum or guinea pig serum resulted in solubilization of IC. When packed human E were added to human serum or guinea pig serum, binding of IC to the E occurred and IC solubilization was significantly inhibited. By contrast, SRBC did not bind IC nor inhibit IC solubilization. Because IC binding to human E is mediated by CR type 1 (CR1) we evaluated whether CR1 was responsible for the inhibition of IC solubilization. Human E were treated with trypsin or anti-CR1 mAb. Both treatments abrogated IC binding to human E but did not affect the ability of the human E to inhibit IC solubilization. Human E inhibited C activation by IC. Thus, incubation of IC in human serum caused significant activation of C3 and C5, but not C4. However, when IC were incubated in whole blood or with isolated human E and serum, C3 activation by IC was inhibited significantly. In addition, we demonstrated that the C3b generated during C activation by IC deposited on both IC and human E. Thus, human E may compete for nascent C3 generated during C activation by IC. In conclusion, human E inhibit both complement-mediated solubilization of IC and C activation by IC.
Incubation of precipitable immune complexes (IC) with fresh human serum or guinea pig serum resulted in solubilization of IC. When packed human E were added to human serum or guinea pig serum, binding of IC to the E occurred and IC solubilization was significantly inhibited. By contrast, SRBC did not bind IC nor inhibit IC solubilization. Because IC binding to human E is mediated by CR type 1 (CR1) we evaluated whether CR1 was responsible for the inhibition of IC solubilization. Human E were treated with trypsin or anti-CR1 mAb. Both treatments abrogated IC binding to human E but did not affect the ability of the human E to inhibit IC solubilization. Human E inhibited C activation by IC. Thus, incubation of IC in human serum caused significant activation of C3 and C5, but not C4. However, when IC were incubated in whole blood or with isolated human E and serum, C3 activation by IC was inhibited significantly. In addition, we demonstrated that the C3b generated during C activation by IC deposited on both IC and human E. Thus, human E may compete for nascent C3 generated during C activation by IC. In conclusion, human E inhibit both complement-mediated solubilization of IC and C activation by IC.
Related Concept Videos
Humoral Immune Responses
Lifecycle of Erythrocytes
The resident phagocytic macrophages deal with these damaged cells by engulfing them and separating their globin and heme groups.
Antibody Actions
Neutralization
Antibodies can bind to pathogens, preventing them from infecting host cells. This process...
Complement System
Hypersensitivity Reactions: Cytolytic Reactions
Hypersensitivity Reactions: Immune-Complex Reactions

