Nucleic acid encoding dendritic cell co-stimulatory molecules
A novel costimulatory protein molecule, B7-DC, which is a member of the B7 family, is described as is DNA coding therefor and expression vectors comprising this DNA. B7-DC protein, fragments, fusion polypeptides/proteins and other functional derivatives, and transformed cells expressing B7-DC are useful in vaccine compositions and methods. Compositions and methods are disclosed for inducing potent T cell mediated responses that can be harnessed for anti-tumor and anti-viral immunity.
1. An isolated nucleic acid molecule that encodes a human or murine B7-DC protein,
wherein the B7-DC protein is selectively expressed on dendritic cells as compared to activated macrophages,
wherein murine B7-DC protein has 32% homology to human B7-H1,
wherein the B7-DC protein comprises single IgV and IgC domains,
wherein the B7-DC protein comprises a single transmembrane domain,
wherein the B7-DC protein comprises an intracytoplasmic tail 4 amino acids in length,
wherein the B7-DC protein does not bind to CD28 or CTLA-4 and does not include the CD28/CTLA-4 binding motifs, and
wherein the B7-DC protein is capable of co-stimulating T cells.
2. The nucleic acid molecule of claim 1 encoding a polypeptide consisting of the extracellular domain of B7-DC.
3. The nucleic acid molecules of claim 2 wherein the polypeptide has the functional activity of the extracellular domain of B7-DC of activating T cells in an allogeneic mixed lymphocyte reaction.
4. The nucleic acid molecule of claim 2 encoding amino acid residues 20-221 of SEQ ID NO:2.
5. A nucleic acid molecule encoding a fusion protein of the extracellular domain of murine or human B7-DC,
wherein the B7-DC protein is selectively expressed on dendritic cells as compared to activated macrophages,
wherein murine B7-DC protein has 32% homology to human B7-H1,
wherein the B7-DC protein comprises single IgV and IgC domains,
wherein the B7-DC protein comprises a single transmembrane domain,
wherein the B7-DC protein comprises an intracytoplasmic tail 4 amino acids in length,
wherein the B7-DC protein does not bind to CD28 or CTLA-4 and does not include the CD28/CTLA-4 binding motifs, and
wherein the B7-DC protein is capable of co-stimulating T cells, with a second polypeptide.
6. The nucleic acid molecule of claim 5 wherein the second polypeptide comprises:
(a) one or more domains of an Ig heavy chain constant region;
(b) two C domains of an IgG heavy chain constant region; or
(c) the hinge, C H 2 and C H 3 regions of a human immunoglobulin Cγ1 chain.
7. The nucleic acid molecule of claim 5 encoding a fusion polypeptide that binds to a binding partner molecule on T cells and co-stimulates the T cells.
8. The nucleic acid molecule of claim 7 wherein the binding partner molecule is a receptor on T cells that is not CD28 or CTLA-4.
9. The nucleic acid molecule of claim 5 wherein the second polypeptide comprises one or more domains of an Ig heavy chain constant region.
10. The nucleic acid molecule of any of claims 1 or 2 - 9 in an expression vector and operatively linked to a promoter, and, optionally, additional regulatory sequences that regulate expression of the nucleic acid in a eukaryotic cell.
11. The nucleic acid molecule of claim 10 wherein the expression vector is a plasmid or a viral vector.
12. An isolated cell comprising the the nucleic acid molecule of claim 10 .
13. The cell of claim 12 wherein the cell is a mammalian cell.
14. A nucleic acid molecule encoding a mature polypeptide comprising a first fusion partner and a second fusion partner, wherein the first fusion partner consists of
the extracellular domain of B7-DC amino acid residues 20-221 of SEQ ID NO:2.
15. The nucleic acid molecule of claim 14 wherein the polypeptide co-stimulates T cells.