Patent ID: 8709755

Claim:
A method of preparing a conditionally active antibody, the method comprising the steps of: i. selecting a wild-type antibody against an antigen; ii. evolving the DNA which encodes the wild-type antibody using one or more evolutionary techniques to create mutant DNAs; iii. expressing the mutant DNAs to obtain at least one mutant antibody; iv. subjecting the at least one mutant antibody and the wild-type antibody to an assay under a normal physiological condition selected from the group consisting of temperature, pH, osmotic pressure, osmolality, oxidation and electrolyte concentration, and to an assay under an aberrant condition selected from the group consisting of temperature, pH, osmotic pressure, osmolality, oxidation and electrolyte concentration; and v. selecting the conditionally active antibody from the at least one mutant antibody which exhibits both (a) a decrease in binding activity to the antigen in the assay at the normal physiological condition compared to the wild-type antibody, and (b) an increase in binding activity to the antigen in the assay under the aberrant condition compared to the wild-type antibody.