Complement Activators r Activation of this pathway may occur via Ag- Ab complex (immune complex, Ic) or by aggregated Ig. r IgG(IgG1, IgG3)and IgM are most efficient in reacting with complement. r Only one molecule of IgM is required, whereas at least two molecules of igg are needed r Soluble antibody cant activate complementActivators Activation of this pathway may occur via Ag￾Ab complex (immune complex, IC) or by aggregated Ig. IgG (IgG1,IgG3) and IgM are most efficient in reacting with complement. Only one molecule of IgM is required, whereas at least two molecules of IgG are needed. Soluble antibody can’t activate complement Complement