Abstract: The invention provides non-human, genetically-modified mammals and genetically modified animals cells having a functionally disrupted P2×7 receptor gene. Also provided are methods for producing genetically modified mice in which one or both P2×7R alleles have been functionally inactivated.

Abstract: Homologous recombination is employed to inactivate genes, particularly genes associated with MHC antigens. Particularly, the &bgr;2-microglobulin gene is inactivated for reducing or eliminating the expression of functional Class I MHC antigens. The resulting cells may be used as universal donor cells. In addition, embryonic stem cells may be modified by homologous recombination for use in producing chimeric or transgenic mammalian hosts, which may be used as source of universal donor organs, or as models for drug and transplantation therapies. Methods for homologous recombination in non-transformed mammalian somatic cells are also described.

Abstract: The invention provides non-human, genetically-modified mammals and genetically modified animals cells having a functionally disrupted P2×7 receptor gene. Also provided are methods for producing genetically modified mice in which one or both P2×7R alleles have been functionally inactivated.

Abstract: Homologous recombination is employed to inactivate genes, particularly genes associated with MHC antigens. Particularly, the .beta..sub.2- microglobulin gene is inactivated for reducing or eliminating the expression of functional Class I MHC antigens. The resulting cells may be used as allogeneic donor cells. Methods for homologous recombination in non-transformed mammalian somatic cells are also described.

Abstract: Homologous recombination is employed to inactivate genes, particularly genes associated with MHC antigens. Particularly, each of the .beta..sub.2- microglobulin gene and the IFN-.gamma.R gene is inactivated for reducing or eliminating the expression of functional MHC antigens. The resulting cells may be used as universal donor cells. In addition, embryonic stem cells may be modified by homologous recombination for use in producing chimeric or transgenic mammalian hosts, which may be used as source of universal donor organs, or as models for drug and transplantation therapies. Methods for homologous recombination in non-transformed mammalian somatic cells are also described.

Abstract: Homologous recombination is employed to inactivate genes, particularly genes associated with MHC antigens. Particularly, the .beta..sub.2 -microglobulin gene is inactivated for reducing or eliminating Class I MHC antigens. The resulting cells may be used as universal donors. In addition, embryonic stem cells may be modified by homologous recombination for use in producing chimeric or transgenic mammalian hosts, which may be used as source of universal donor organs.

Abstract: Homologous recombination is employed to inactivate genes, particularly genes associated with MHC antigens. Particularly, the .beta..sub.2 -microglobulin gene is inactivated for reducing or eliminating Class I MHC antigens. The resulting cells may be used as universal donors. In addition, embryonic stem cells may be modified by homologous recombination for use in producing chimeric or transgenic mammalian hosts, which may be used as source of universal donor organs, or as models for drug and transplantation therapies.

Abstract: HLA class I and class II locus specific DNA probes are prepared by cloning DNA segments obtained from the 3'-untranslated region and the 5' flanking region of isolated alleles. The probes are useful to determine the HLA alleles present in an individual.