title: Chimeric and humanized antibodies with specificity for the CD33 antigen.
abstract: L and H chain cDNAs of M195, a murine mAb that binds to the CD33 Ag on normal and leukemic myeloid cells, were cloned. The cDNAs were used in the construction of mouse/human IgG1 and IgG3 chimeric antibodies. In addition, humanized antibodies were constructed which combined the complementarity-determining regions of the M195 antibody with human framework and constant regions. The human framework was chosen to maximize homology with the M195 V domain sequence. Moreover, a computer model of M195 was used to identify several framework amino acids that are likely to interact with the complementarity-determining regions, and these residues were also retained in the humanized antibodies. Unexpectedly, the humanized IgG1 and IgG3 M195 antibodies, which have reshaped V regions, have higher apparent binding affinity for the CD33 Ag than the chimeric or mouse antibodies.
authors.affiliation: Protein Design Labs, Inc., Mountain View, CA 94043.
authors.forename: M S
authors.initials: MS
authors.lastname: Co
authors.forename: N M
authors.initials: NM
authors.lastname: Avdalovic
authors.forename: P C
authors.initials: PC
authors.lastname: Caron
authors.forename: M V
authors.initials: MV
authors.lastname: Avdalovic
authors.forename: D A
authors.initials: DA
authors.lastname: Scheinberg
authors.forename: C
authors.initials: C
authors.lastname: Queen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics* / Q000276:immunology; D000915:Antibody Affinity; D015703:Antigens, CD / Q000276:immunology*; D015214:Antigens, Differentiation, Myelomonocytic / Q000276:immunology*; D001483:Base Sequence; D003001:Cloning, Molecular; D006801:Humans; D007074:Immunoglobulin G / Q000235:genetics* / Q000276:immunology; D007135:Immunoglobulin Variable Region / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000276:immunology*; D063268:Sialic Acid Binding Ig-like Lectin 3
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; C571163:CD33 protein, human; C571165:Cd33 protein, mouse; D007074:Immunoglobulin G; D007135:Immunoglobulin Variable Region; D011993:Recombinant Fusion Proteins; D063268:Sialic Acid Binding Ig-like Lectin 3