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Depletion of Specific Cell Populations by Complement Depletion
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Engineered antibodies with increased activity to recruit complement

E E Idusogie1, P Y Wong, L G Presta

  • 1Oncology Department, Aventis-Gencell, Hayward, CA 94545, USA.

Journal of Immunology (Baltimore, Md. : 1950)
|February 13, 2001
PubMed

This manuscript describes two sites in a human IgG1 that, when mutated individually or in combination, result in a dramatic increase in C1q binding and complement-dependent cytotoxicity activity. These two residues, K326 and E333, are located at the extreme ends of the C1q binding epicenter in the C(H)2 domain of a human IgG. A mutation to tryptophan at K326 debilitates Ab-dependent cell-mediated cytotoxicity activity. In addition, substitutions of the residues E333 with serine and of K326 with tryptophan in a human IgG2 confer biological activity in the complement-dependent cytotoxicity assay in which the wild-type IgG2 is inactive. This study reveals that the residues K326 and E333 play a significant role in the control of the biological activity of an IgG molecule and can rescue the activity of an inactive IgG isotype.

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