Regeneron Pharmaceuticals, Inc.
Methods for determining cell killing by a human therapeutic

Abstract:

Genetically modified non-human animals and methods and compositions for making and using them are provided, wherein the genetic modification comprises a deletion of the endogenous low affinity Fc.gamma.R locus, and wherein the mouse is capable of expressing a functional FcR.gamma.-chain. Genetically modified mice are described, including mice that express low affinity human Fc.gamma.R genes from the endogenous Fc.gamma.R locus, and wherein the mice comprise a functional FcR.gamma.-chain. Genetically modified mice that express up to five low affinity human Fc.gamma.R genes on accessory cells of the host immune system are provided.