Abstract: It is an object of the present invention to provide an immunodeficient animal capable of generating human-derived lymphoid cells, a human-derived lymphoid cell, and a method for producing a human antigen-specific antibody. The means for solving the aforementioned object is: an immature immunodeficient mammal into which human-derived hematopoietic precursor cells have been transplanted, and which is able to generate said human-derived hematopoietic cells or immunocompetent cells; and a method for producing a human-derived antibody, which is characterized in that it comprises recovering immunocompetent cells from the above-described mammal, culturing the immunocompetent cells, and collecting a human-derived antibody from the obtained culture product.

Abstract: The present invention provides Epstein-Barr virus (EBV)-negative NK cell lines. The NK cell lines of the present invention are useful for screening factors associated with the proliferation and expression functions of NK cells and to discover factors produced by the NK cells. In addition, the cell lines are immortalized despite the fact that they are EBV-negative. Thus, unknown mechanisms of oncogenesis may be elucidated through an understanding of the mechanisms underlying the immortalization of the cell lines of the present invention.

Abstract: It is an object of the present invention to provide an immunodeficient animal capable of generating human-derived lymphoid cells, a human-derived lymphoid cell, and a method for producing a human antigen-specific antibody. The means for solving the aforementioned object is: an immature immunodeficient mammal into which human-derived hematopoietic precursor cells have been transplanted, and which is able to generate said human-derived hematopoietic cells or immunocompetent cells; and a method for producing a human-derived antibody, which is characterized in that it comprises recovering immunocompetent cells from the above-described mammal, culturing the immunocompetent cells, and collecting a human-derived antibody from the obtained culture product.

Abstract: It is intended to provide a method of regenerating an organ or a part thereof which comprises transplanting bone marrow or hematopoietic stem cells into an injured mammal or a mammal having an injured in organ or a part thereof; a method of treating injury: a method of producing an organ or a part thereof; and an organ or a part thereof produced by this method.

Abstract: The present invention provides Epstein-Barr virus (EBV)-negative NK cell lines. The NK cell lines of the present invention are useful for screening factors associated with the proliferation and expression functions of NK cells and to discover factors produced by the NK cells. In addition, the cell lines are immortalized despite the fact that they are EBV-negative. Thus, unknown mechanisms of oncogenesis may be elucidated through an understanding of the mechanisms underlying the immortalization of the cell lines of the present invention.