Effect of multivalent interactions antibody Fab IgG IgG IgM effective antibody valence 1 2 up to 10 antigen valence 1 1 n n equilibrium constant (L/M) 104 104 107 1011 advantage of multi-valence 103-fold 107-fold definition of bindng affinity affinity avidity avidity intrinsic affinity functional affinity Effect of multivalent interactions antibody Fab IgG IgG IgM effective antibody valence 1 1 2 up to 10 antigen valence 1 1 n n equilibrium constant (L/M) 104 104 107 1011 advantage of multi-valence - - 103-fold 107-fold definition of bindng affinity affinity avidity avidity intrinsic affinity functional affinity