Low affinity FCGR deficient mice
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 FcγR locus, and wherein the mouse is capable of expressing a functional FcRγ-chain. Genetically modified mice are described, including mice that express low affinity human FcγR genes from the endogenous FcγR locus, and wherein the mice comprise a functional FcRγ-chain. Genetically modified mice that express up to five low affinity human FcγR genes on accessory cells of the host immune system are provided.
1. A transgenic mouse whose genome comprises a human nucleotide sequence that encodes at least two contiguous FcγR α-chain genes selected from a human FcγRIIA α-chain gene, a human FcγRIIB α-chain gene, a human FcγRIIC α-chain gene, a human FcγRIIIA α-chain gene, a human FcγRIIIB α-chain gene, and a combination thereof, wherein the human nucleotide sequence replaces mouse FcγR α-chain gene sequences in a mouse FcγR locus, and wherein the mouse comprises a functional FcR γ-chain gene and expresses the at least two contiguous FcγR α-chain genes.
2. The mouse of claim 1 , wherein the at least two contiguous α-chain genes are a human FcγRIIA α-chain gene and a human FcγRIIIA α-chain gene.
3. The mouse of claim 2 , wherein the human FcγRIIIA α-chain gene encodes a FcγRIIIA α-chain protein that comprises a phenylalanine at amino acid position 158.
4. The mouse of claim 2 , wherein the human FcγRIIIA α-chain gene encodes a FcγRIIIA α-chain protein that comprises a valine at amino acid position 158.
5. The mouse of claim 1 , wherein the at least two contiguous human α-chain genes are selected from a human FcγRIIB α-chain gene, a human FcγRIIC α-chain gene, a human FcγRIIIB α-chain gene, and a combination thereof.
6. The mouse of claim 2 , wherein the human FcγRIIIA α-chain gene encodes a human FcγRIIIA α-chain protein that is expressed on NK cells of the mouse.
7. A method of screening an agent comprising an Fc region of a human antibody comprising:
(a) administering an agent comprising an Fc region of a human antibody to the transgenic mouse of claim 1 , wherein the agent binds to a target cell in the mouse;
(b) measuring antibody-dependent cell-mediated cytotoxicity (ADCC) of natural killer (NK) cells against the target cell; and
(c) comparing the amount of ADCC in step (b) to a control, wherein increased target cell killing indicates the agent has increased ability to mediate ADCC.
8. The method of claim 7 , wherein the human nucleotide sequence encodes a human FcγRIIA α-chain gene and a human FcγRIIIA α-chain gene.
9. The method of claim 7 , wherein the target cell is a tumor cell and the agent binds an epitope of the tumor cell.
10. The method of claim 7 , wherein the target cell is a mouse cell infected by a human pathogen and the agent binds an epitope of the human pathogen.
11. The method of claim 7 , wherein the target cell is a human cell infected by a human pathogen and the agent binds an epitope of the human pathogen.
12. The method of claim 7 , wherein the target cell is a human tumor cell and the agent binds an epitope of the human tumor cell.
13. The method of claim 7 , wherein the ADCC of NK cells against the target cell is measured in a blood sample of the mouse.
14. The method of claim 7 , wherein the agent is an antibody.
15. The method of claim 14 , wherein the antibody is a human antibody.