Transgenic mice expressing human CD20 and/or CD16

1. A transgenic mouse whose genome comprises a first nucleotide sequence encoding human CD20 and a second nucleotide sequence encoding a subunit of a heterologous FcγIII receptor (CD16), wherein the first nucleotide sequence is operably linked to a CD20 promoter, and wherein the second nucleotide sequence is operably linked to a FcγIII receptor promoter.

2. The transgenic mouse of claim 1 , wherein said CD20 promoter is a human promoter.

3. The transgenic mouse of claim 2 , whose cells express human CD20.

4. The transgenic mouse of claim 3 , wherein human CD20 is expressed on the surface of B lymphocytes.

5. The transgenic mouse of claim 2 , wherein said FcγIII receptor promoter is a human promoter.

6. The transgenic mouse of claim 1 , wherein said second nucleotide sequence encodes human CD16 alpha chain subtype A.

7. The transgenic mouse of claim 6 , wherein said receptor is expressed on the surface of leucocytes.

8. The transgenic mouse of claim 1 , wherein said receptor is expressed on the surface of one or more cells selected from the group consisting of NK cells, macrophages, neutrophils, eosinophils, basophils, mast cells, and thymocyte cells.

9. The transgenic mouse of claim 1 , wherein the genome of said mouse further comprises a disruption in an endogenous gene encoding a subunit of a receptor substantially homologous to the heterologous FcγIII receptor (CD16).

10. The transgenic mouse of claim 9 , wherein the endogenous gene encodes a mouse CD16 alpha chain.

11. A method of identifying an agent capable of treating a B cell lymphoma said method comprising:

a) measuring the level of B lymphocytes expressing human CD20 in a mouse of claim 1 ;

b) administering said agent to the mouse of claim 1 ; and

c) measuring the level of B lymphocytes expressing human CD20 in the mouse; wherein a decrease in the number of B lymphocytes expressing human CD20 in the mouse after treatment with the agent identifies the agent capable of treating a B cell lymphoma.

12. A method of identifying an agent capable of depleting or killing cells expressing human CD20 said method comprising:

a) measuring the level of B lymphocytes expressing human CD20 in a mouse of claim 1 ;

b) administering said agent to the mouse of claim 1 ; and

c) measuring the level of B lymphocytes expressing human CD20 in the mouse;

wherein a decrease in the number of B lymphocytes expressing human CD20 in the mouse identifies the agent as capable of depleting or killing cells expressing CD20.

13. The method of claim 12 wherein said cells are cancer cells.

14. A cell or tissue derived from the transgenic mouse of claim 1 .

15. A method of identifying an agent capable of inducing an Fc-mediated effector cell response said method comprising

a) measuring the baseline level of one or more cytokines associated with an Fc-mediated effector cell response in a transgenic mouse of claim 1 ;

b) administering said agent to the transgenic mouse;

c) measuring the level of the cytokines in the mouse; wherein an increase in the level of cytokines after administration identifies the agent as capable of inducing an Fc-mediated effector cell response.

16. A method of identifying an agent capable of inducing an Fc-mediated effector cell response against B lymphocytes expressing human CD20, said method comprising:

a) measuring the level of B lymphocytes expressing human CD20 in a first transgenic mouse whose genome comprises a nucleotide sequence encoding human CD20 and operably linked to a CD20 promoter;

b) administering said agent to the first transgenic mouse;

c) measuring the level of B lymphocytes expressing human CD20 in the first transgenic mouse;

d) determining the percent reduction in the level of B lymphocytes between step (a) and step (c);

e) measuring the level of B lymphocytes expressing human CD20 in a second transgenic mouse of claim 1 ;

f) administering said agent to the second transgenic mouse of claim 1 ;

g) measuring the level of B lymphocytes expressing human CD20 in the second transgenic mouse; and

h) determining the percent reduction in the level of B lymphocytes between step (e) and step (g);

wherein if the percent reduction determined in step (h) is greater than the percent reduction determined in step (d), the agent is identified as capable of inducing an Fc-mediated effector cell response against B lymphocytes expressing human CD20.

17. A method of testing safety of anti-human CD20 therapy, said method comprising:

a) measuring the level of B lymphocytes expressing human CD20 in a mouse of claim 1 ;

b) administering said agent to the mouse of claim 1 ; and

c) measuring the level of B lymphocytes expressing human CD20 in the mouse; wherein a decrease in the number of B lymphocytes expressing human CD20 in the mouse identifies the agent as capable of depleting or killing cells expressing CD20;

d) monitoring the mouse for short or long term adverse effects.

18. A method of testing efficacy of anti-human CD20 therapy, said method comprising:

a) measuring the level of B lymphocytes expressing human CD20 in a set of mice of claim 1 ;

b) administering to each mouse of the set a different dose of an agent; and

c) measuring the level of B lymphocytes expressing human CD20 in the mouse after each dose; and

d) determining at least one dose of the agent that results in the most B cell depletion.

19. The transgenic mouse of claim 1 , wherein the first nucleotide sequence is operably linked to a mouse promoter.

20. The transgenic mouse of claim 1 , wherein the second nucleotide sequence is operably linked to a mouse promoter.

21. The cell or tissue of claim 14 , wherein the cell or tissue expresses human CD20.

22. The cell or tissue of claim 14 , wherein the cell or tissue expresses a subunit of human FcγIII receptor (CD16).

23. The transgenic mouse of claim 6 , wherein the human CD20 is expressed on the surface of B lymphocytes and human CD16 alpha chain subtype A is expressed on the surface of leucocytes in the transgenic mouse.