Genetically-engineered MHC molecules
The invention provides DNA molecules encoding a chimeric polypeptide comprising (a) a component of a MHC molecule capable of association on a cell surface with an endogenous MHC molecule component of the same class, and (b) an intracellular region of a signal transduction element capable of activating T cells. Component (a) may be a monomorphic component and is preferably beta 2-microglobulin, or a polymorphic class I or class II component. The signal transduction element (b) capable of activating T cells may be a component of T-cell receptor CD3, preferably the CD3 zeta (zeta) polypeptide, a B cell receptor polypeptide or an Fc receptor polypeptide. Immune cells such as a CTLs expressing said chimeric MHC molecules specifically eliminate or inactivate harmful T cells and are useful for treating graft rejection and autoimmune diseases.
1. A DNA molecule encoding a chimeric polypeptide comprising (a) a component of a MHC molecule capable of association on a cell surface with an endogenous MHC molecule component of the same class, and (b) an intracellular region of a signal transduction element capable of activating T cells, wherein said signal transduction element is a component of T cell receptor CD3 and said component of T-cell receptor CD3 comprises the transmembranal and cytoplasmic regions of the human zeta (ζ) polypeptide.
2. The DNA molecule of claim 1 , wherein said MHC component (a) is a monomorphic component selected from the group consisting of β 2 -microglobulin and the monomorphic α chain of a HLA-DR molecule.
3. The DNA molecule of claim 2 , wherein said MHC component (a) is human β 2 -microglobulin capable of association on a cell surface with an endogenous class I heavy chain HLA molecule, and said β 2 -microglobulin is linked to component (b) by a bridge peptide having about 10-15 amino acid residues.
4. The DNA molecule of claim 3 , wherein said bridge peptide has a sequence comprised within the membrane-proximal sequence of a class I heavy chain HLA molecule.
5. The DNA molecule of claim 4 , wherein said bridge peptide has 13 amino acid residues comprised within the extracellular membrane-proximal sequence of the class I heavy chain HLA-A2 molecule, and has the sequence: Leu Arg Trp Glu Pro Ser Ser Gln Pro Thr Ile Pro Ile (SEQ ID NO:9).
6. The DNA molecule of claim 2 , wherein said MHC component (a) is a monomorphic α chain of a HLA-DR molecule.
7. The DNA molecule of claim 1 , wherein said MHC component (a) is a polymorphic component selected from the group consisting of: (i) an α chain of class I HLA-A, HLA-B or HLA-C molecule, which is capable of association on a cell surface with endogenous β 2 m; (ii) an α chain of class II HLA-DP or HLA-DQ molecule, which is capable of association on a cell surface with endogenous HLA-DPβ or HLA-DQβ chain; or (iii) a β chain of class II HLA-DP, HLA-DR or HLA-DQ molecule, which is capable of association on a cell surface with an endogenous HLA-DPα, HLA-DRα or HLA-DQα chain.
8. The DNA molecule of claim 1 , wherein said chimeric polypeptide further comprises an antigenic peptide related to an autoimmune disease, said antigenic peptide being linked to said chimeric polypeptide by a peptide linker.
9. The DNA molecule of claim 8 , wherein said antigenic peptide has 8-10 amino acid residues and binds to a product of a certain HLA allele.
10. An isolated immune cell which expresses a chimeric polypeptide as defined in claim 9 and binds to an lyses autoreactive cells causing an autoimmune disease.
11. An isolated immune cell which expresses a chimeric polypeptide as defined in claim 8 and binds to and lyses autoreactive cells causing an autoimmune disease.
12. A vector comprising the DNA molecule of claim 1 .
13. An isolated immune cell which expresses a chimeric polypeptide as defined in claim 1 and binds to, and eliminates, alloreactive cells causing transplant rejection.
14. The immune cell of claim 13 which is a cytotoxic T lymphocyte (CTL).
15. The cell which expresses a chimeric polypeptide comprising (a) a component of a MHC molecule capable of association on a cell surface with an endogenous MHC molecule component of the same class, and (b) an intracellular region of a signal transduction element capable of activating T cells, wherein said signal transduction element is a component of T-Cell receptor CD3 and said component of T-cell receptor CD3 comprises the transmembranal and cytoplasmic regions of the human zeta (ζ) polypeptide.
16. The cell of claim 15 , wherein said cell is an immune cell selected from the group consisting of T helper cells (CD4 + ), cytotoxic T lymphocytes (CD8 + ) and natural killer (NK) cells, capable of recognizing and binding to harmful T cells and causing their lysis or inactivation.