CELL

1 . A cell which comprises:

(i) a chimeric antigen receptor (CAR) or a transgenic T-cell receptor (TCR); and

(ii) at least one polypeptide capable of co-localizing an MHC class I polypeptide or an MHC class II polypeptide with an intracellular signalling domain within the cell.

2 - 4 . (canceled)

5 . A cell according to claim 1 , which comprises:

(i) a chimeric antigen receptor (CAR) or a transgenic T-cell receptor (TCR); and

(ii) an engineered polypeptide which comprises a binding domain which is binds to an MHC class I polypeptide or an MHC class II polypeptide linked to an intracellular signalling domain.

6 . A cell according to claim 1 , which comprises:

(i) a chimeric antigen receptor (CAR) or a transgenic T-cell receptor (TCR); and

(ii) an engineered polypeptide which comprises CD79α or CD79β linked to an intracellular signalling domain.

7 . A cell according to claim 1 , which comprises:

(i) a chimeric antigen receptor (CAR) or a transgenic T-cell receptor (TCR); and

(ii) an engineered polypeptide which comprises the MHC class II-binding domain of CD4 linked to an intracellular signalling domain.

8 . A cell according to claim 7 , wherein the MHC class II-binding domain of CD4 comprises one or more mutations to increase its binding affinity for the β2 region of MHC class II.

9 . A cell according to claim 8 , wherein the MHC class II-binding domain of CD4 comprises substitution mutations Gln40Tyr and/or Thr45Trp with reference to SEQ ID No. 47.

10 . A cell according to claim 1 , which comprises:

(i) a chimeric antigen receptor (CAR) or a transgenic T-cell receptor (TCR); and

(ii) an engineered polypeptide which comprises the MHC class I-binding domain of CD8 linked to an intracellular signalling domain.

11 . A cell according to claim 1 , which comprises:

(i) a chimeric antigen receptor (CAR) or a transgenic T-cell receptor (TCR); and expresses

(ii) a bispecific polypeptide which comprises;

(a) a first binding domain which is binds to an MHC class I polypeptide or an MHC class II polypeptide; and

(b) a second binding domain which binds to a polypeptide comprising an intracellular signalling domain or a component of the CD3 complex.

12 . A cell according to claim 11 , wherein the bispecific polypeptide is membrane-tethered.

13 . A nucleic acid construct which comprises:

(i) a first nucleic acid sequence which encodes a chimeric antigen receptor (CAR) or a transgenic TCR; and

(ii) a second nucleic acid sequence which encodes an engineered polypeptide which, when expressed in a cell, is capable of co-localizing an MHC class I polypeptide or an MHC class II polypeptide with an intracellular signaling domain within the cell.

14 . A nucleic acid construct according to claim 13 wherein the first and second nucleic acid sequences are separated by a co-expression site.

15 . (canceled)

16 . A vector which comprises a nucleic acid construct according to claim 13 .

17 . (canceled)

18 . A pharmaceutical composition which comprises a plurality of cells according to claim 1 .

19 . (canceled)

20 . A method for treating a disease, which comprises the step of administering a pharmaceutical composition according to claim 18 to a subject.

21 - 22 . (canceled)

23 . A method for making a cell according to claim 1 , which comprises the step of introducing:

(i) a first nucleic acid sequence which encodes a chimeric antigen receptor (CAR) or a transgenic TCR; and

(ii) a second nucleic acid sequence which encodes an engineered polypeptide which, when expressed in a cell, is capable of co-localizing an MHC class I polypeptide or an MHC class II polypeptide with an intracellular signalling domain within the cell, into a cell ex vivo.

24 . A method for depleting alloreactive immune cells from a population of immune cells, which comprises the step of contacting the population of immune cells with a plurality of cells which express an engineered polypeptide capable of co-localizing an MHC class I polypeptide or an MHC class II polypeptide with an intracellular signaling domain within the cell.

25 - 28 . (canceled)