title: Complement-mediated adherence of immune complexes to human erythrocytes. Difference in the requirements for C4A and C4B.
abstract: The classical pathway of complement is required for the adherence of soluble tetanus toxoid (TT)-human anti-TT complexes to erythrocytes. Using human C4-deficient serum we compared the capacity of the two forms of human C4 (C4A and C4B) to mediate this function: C4A was shown to be 1.5-fold more efficient than C4B. In contrast, haemolysis by C4B was 3.7-fold more efficient than by C4A. Such large differences suggest that both forms are complementary, and that C4A is preferentially involved in the processing of immune complexes in humans.
mesh_terms: D000906:Antibodies / Q000276:immunology; D000936:Antigen-Antibody Complex / Q000276:immunology*; D003181:Complement C4 / Q000276:immunology*; D015934:Complement C4a; D015935:Complement C4b; D003171:Complement Pathway, Classical; D004912:Erythrocytes / Q000276:immunology*; D006801:Humans; D007700:Kinetics; D013745:Tetanus Toxoid / Q000276:immunology
chemical_list: D000906:Antibodies; D000936:Antigen-Antibody Complex; D003181:Complement C4; D013745:Tetanus Toxoid; D015934:Complement C4a; D015935:Complement C4b