Novel receptor-type tyrosine kinase ligand

摘要

A novel receptor-type tyrosine kinase ligand binding to the extracellular part of a specified receptor-type tyrosine kinase to enhance the enzymatic activity of the tyrosine kinase in the intracellular part to thereby induce tyrosine kinase phosphorylation, which specified kinase is one that expresses in undifferentiated blood cells but suffers from a lowering in the expression level with the progress of the differentiation of the blood cells and that participates in the differentiation and growth of the undifferentiated cells; a complex of the above novel ligand with at least one member selected from the group consisting of the ligand and other compounds; a DNA coding for the ligand; a genetic-engineering process for producing the ligand; and an antibody that specifically recognizes the ligand. The effect of the ligand in accelerating the growth of undifferentiated blood cells is based on the acceleration of colony formation of human cord blood monocytes. As the ligand and complex thereof have the effect of accelerating the differentiation and growth of undifferentiated blood cells, they are useful for the study of the problems related to undifferentiated blood cells including hematopoietic stem cells, such as leukemia and bone marrow transplantation, and for the therapy.