Methods of using humanized FCγR mice to assay Fc regions
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 method for using immune cells from a genetically modified mouse in an antibody-dependent cell-mediated cytotoxicity (ADCC) assay, the method comprising:
(a) obtaining immune cells from a genetically modified mouse that has been administered a protein that comprises a constant fragment (Fc) of a human antibody, wherein the mouse genome comprises at least two low affinity human FcγR α-chain genes that replace one or more endogenous mouse low affinity FcγR α-chain genes, wherein the mouse expresses a functional endogenous mouse FcR γ-chain, and wherein the mouse functionally expresses the at least two low affinity human FcγR α-chain genes; and
(b) using the immune cells in an in vitro ADCC assay.
2. The method of claim 1 , wherein the at least two low affinity human FcγR α-chain genes comprise a human FcγRIIA α-chain gene and a human FcγRIIIA α-chain gene.
3. The method of claim 2 , wherein the human FcγRIIA α-chain gene encodes a FcγRIIA α-chain with a 131Arg polymorphism.
4. The method of claim 2 , wherein the human FcγRIIA α-chain gene encodes a FcγRIIA α-chain with a 131His polymorphism.
5. The method of claim 2 , wherein the human FcγRIIIA α-chain gene encodes a FcγRIIA α-chain with a 158Val polymorphism.
6. The method of claim 2 , wherein the human FcγRIIIA α-chain gene encodes a FcγRIIA α-chain with a 158Phe polymorphism.
7. The method of claim 2 , wherein the human FcγRIIIA α-chain genes are expressed by NK cells in the mouse.
8. The method of claim 1 , wherein the at least two low affinity human FcγR α-chain genes comprise a human FcγRIIB α-chain gene, a human FcγRIIC α-chain gene, and a human FcγRIIIB α-chain gene.
9. The method of claim 8 , wherein the human FcγRIIB α-chain gene encodes a FcγRIIB α-chain with a 232Ile polymorphism.
10. The method of claim 8 , wherein the human FcγRIIB α-chain gene encodes a FcγRIIB α-chain with a 232Thr polymorphism.
11. The method of claim 1 , wherein the at least two low affinity human FcγR α-chain genes comprise a human FcγRIIA α-chain gene, a human FcγRIIIA α-chain gene, a human FcγRIIB α-chain gene, a human FcγRIIC α-chain gene, and a human FcγRIIIB α-chain gene.
12. The method of claim 1 , wherein the protein is a human antibody.
13. The method of claim 12 , wherein the human antibody targets a tumor cell.
14. The method of claim 12 , wherein the human antibody targets a cell infected by a pathogen.
15. The method of claim 1 , wherein the immune cells are natural killer (NK) cells.
16. The method of claim 15 , wherein the immune cells are obtained from blood.
17. The method of claim 1 , wherein the one or more endogenous mouse low affinity FcγR α-chain genes comprise an endogenous FcγRIIB α-chain gene, an endogenous FcγRIV α-chain gene, and/or an endogenous FcγRIII α-chain gene.
18. The method of claim 1 , wherein the at least two low affinity human FcγR α-chain genes replace an endogenous FcγRIIB α-chain gene, an endogenous FcγRIV α-chain gene, and an endogenous FcγRIII α-chain gene.
19. The method of claim 11 , wherein the at least two low affinity human FcγR α-chain genes replace an endogenous FcγRIIB α-chain gene, an endogenous FcγRIV α-chain gene, and an endogenous FcγRIII α-chain gene.