Compositions and methods for modulation of antibody activity

An allosteric antibody comprising at least three amino acid substitutions at positions corresponding to Trp110 and Val37 in the heavy chain and a substitution corresponding to Phe98 in its light chain within an antigen-binding antibody, wherein the numbering is based on the positioning in the 4D5Flu antibody, wherein said amino acid substitutions form a contiguous cavity within the allosteric antibody which can be bound by an effector molecule, wherein the effector molecule comprises the amino acid side chains, or analog thereof, that were removed from the antibody by the at least three substitutions, wherein the allosteric antibody has reduced binding affinity for antigen, and wherein the binding affinity of the allosteric antibody for antigen is increased or restored upon binding with an effector molecule.