Ligand for the c-kit receptor and methods of use thereof

Abstract

This invention provides an isolated nucleic acid molecule which encodes an amino acid sequence corresponding to a c-kit ligand (KL) and a purified c-kit ligand (KL) polypeptide, or a soluble fragment thereof. A pharmaceutical composition which comprises the c-kit ligand (KL) purified by applicants or produced by applicants' recombinant methods and a pharmaceutically acceptable carrier is further provided as well as methods of treating patients which comprise administering to the patient the pharmaceutical composition of this invention.

What is claimed is:  
     
         1 . An isolated nucleic acid molecule which encodes an amino acid sequence corresponding to a c-kit ligand (KL).  
     
     
         2 . An isolated nucleic acid molecule of  claim 1 , wherein the c-kit ligand (KL) is a human c-kit ligand (KL).  
     
     
         3 . An isolates nucleic acid molecule of  claim 1 , wherein the c-kit ligand (KL) is a murine c-kit ligand (KL).  
     
     
         4 . An isolated nucleic acid molecule of  claim 1 , wherein the isolated nucleic acid molecule is a DNA molecule.  
     
     
         5 . The DNA molecule  claim 4 , wherein the DNA molecule is a cDNA molecule.  
     
     
         6 . An isolated nucleic acid molecule of  claim 1 , wherein the isolated nucleic acid molecule is an RNA molecule.  
     
     
         7 . The isolated nucleic acid molecule of  claim 4  wherein the isolated nucleic acid molecule is operatively linked to a promoter of RNA transcription.  
     
     
         8 . A vector which comprises the isolated nucleic acid molecule of  claim 1 .  
     
     
         9 . A vector of  claim 8  which comprises a plasmid.  
     
     
         10 . A vector of  claim 8  which comprises a virus.  
     
     
         11 . A host vector system for the production of an amino acid sequence which is the c-kit ligand which comprises the plasmid of  claim 9  in a suitable host.  
     
     
         12 . A host vector system of  claim 11 , wherein the suitable host is a eucaryotic cell.  
     
     
         13 . A host vector system of  claim 13 , wherein the eucaryotic cell is a mammalian cell.  
     
     
         14 . A host vector system of  claim 13 , wherein the eucaryotic cell is an insect cell.  
     
     
         15 . A host vector system of  claim 13 , wherein the eucaryotic cell is a yeast cell.  
     
     
         16 . A host vector system of  claim 11 , wherein the suitable host is a procaryotic cell.  
     
     
         17 . An isolated c-kit ligand (KL) polypeptide.  
     
     
         18 . A soluble c-kit ligand (KL) polypeptide wherein the soluble, c-kit ligand (KL) polypeptide comprises a fragment of the isolated c-kit ligand (KL) polypeptide of  claim 17 .  
     
     
         19 . A soluble, mutated, c-kit ligand (KL) polypeptide wherein the biological activity mediated by the binding of the ligand to the receptor is destroyed.  
     
     
         20 . A substance capable of specifically forming a complex with the soluble, c-kit ligand (KL) polypeptide of  claim 18 .  
     
     
         21 . The substance of  claim 20 , wherein the substance is a monoclonal antibody.  
     
     
         22 . The substance of  claim 21 , wherein the monoclonal antibody is a human monoclonal antibody.  
     
     
         23 . The soluble, c-kit ligand (KL) polypeptide of  claim 17  conjugated to an imageable agent.  
     
     
         24 . The soluble, c-kit ligand (KL) polypeptide of  claim 23 , wherein imageable agent is selected from the group consisting of radioisotopes, dyes or enzymes.  
     
     
         25 . The soluble, c-kit ligand (KL) polypeptide of  claim 18  conjugated to a therapeutic agent.  
     
     
         26 . The soluble, c-Kit ligand (KL) polypeptide of  claim 25 , wherein the therapeutic agent is selected from the group consisting of toxins, chemotherapeutic agents or radioisotopes.  
     
     
         27 . A method for producing a c-kit ligand (KL) polypeptide which comprises growing the host vector system of  claim 11  under suitable conditions permitting production of the c-kit ligand (KL) polypeptide and recovering the resulting c-kit ligand (KL) polypeptide.  
     
     
         28 . The c-kit ligand (KL) produced by the method of  claim 27 .  
     
     
         29 . A Pharmaceutical composition which comprises the soluble, mutated c-kit ligand of  claim 19  and a pharmaceutically acceptable carrier.  
     
     
         30 . A pharmaceutical composition which comprises the soluble, c-kit ligand (KL) of  claim 18  and a pharmaceutically acceptable carrier.  
     
     
         31 . A method of modifying a biological function associated with c-kit cellular activity which comprises contacting cells, whose function is to be modified, with an effective amount of the pharmaceutical composition of  claim 30 , effective to modify the biological function of the cells.  
     
     
         32 . The method of  claim 31 , wherein the biological function is the propagation of a cell that expresses c-kit.  
     
     
         33 . The method of  claim 32 , wherein the cell which expresses c-kit is a hematopoietic cell.  
     
     
         34 . The method of  claim 31 , wherein the biological function is in vitro fertilization.  
     
     
         35 . A method of modifying a biological function associated with c-kit cellular activity in a patient which comprises administering to the patient an effective amount of the pharmaceutical composition of  claim 30 , effective to modify the biological function associated with c-kit function.  
     
     
         36 . A method of stimulating the proliferation of mast cells in a patient which comprises administering to the patient an effective amount of the pharmaceutical composition of  claim 30 , effective to stimulate the proliferation of the mast cells in the patient.  
     
     
         37 . A method of inducing differentiation of mast cells in a patient which comprises administering to the patient an effective amount of the pharmaceutical composition of  claim 30 , which is effective to induce differentiation of the mast cells.  
     
     
         38 . A method of inducing differentiation of erythroid progenitors in a patient which comprises administering the patient an effective amount of the pharmaceutical composition of  claim 30 , which is effective to induce differentiation of the erythroid progenitors.  
     
     
         39 . A method of facilitating bone marrow transplantation in a patient which comprises administering to the patient an effective amount of the pharmaceutical composition of  claim 30 , effective to facilitate bone marrow transplantation.  
     
     
         40 . A method of treating leukemia in a patient which comprises administering to the patient an effective amount of the pharmaceutical composition of  claim 30 , effective to treat the leukemia.  
     
     
         41 . A method of treating leukemia according to  claim 40 , wherein the leukemia is acute myelogenous leukemia.  
     
     
         42 . A method of treating leukemia according to  claim 40 , wherein the leukemia is chronic myelogenous leukemia.  
     
     
         43 . A method of treating allergies in a patient which comprises administering to the patient an effective amount of the pharmaceutical composition of  claim 29 , effective to treat the allergy.  
     
     
         44 . A method of treating melanoma in a patient, which comprises administering to the patient an effective amount of the composition of  claim 30 , effective to treat the melanoma.  
     
     
         45 . A method for measuring the biological activity of a c-kit (KL) polypeptide which comprises: 
 a) incubating normal bone-marrow mast cells with a sample of the c-kit ligand (KL) polypeptide under suitable conditions such that the proliferation of the normal bone-marrow mast cells are induce ;    b) incubating doubly mutant bone-marrow mast cells with a sample of the c-kit ligand (KL) polypeptide under suitable conditions;    c) incubating a. and b. with  3 H-thymidine;    d) determining the amount of thymidine incorporated into the DNA of the normal bone-marrow mast cells and the doubly mutant bone-marrow mast cells; and    e) comparing the amount of incorporation of thymidine into the normal bone-marrow mast cells against the amount of corporation of thymidine into doubly mutant bone-marrow mast cells, thereby measuring the bioligical activity of c-kit ligand (KL) polypeptide.