A 320-Kilobase Artificaial Chromosome Enocoding the Human HLA DR3-DQ2 MHC Haplotype Confers HLA Restriction in Transgenic Mice~1

摘要

MHC class II haplotypes control the specificity of Th immune responses and susceptibility to many autoimmune diseases. Understanding the role of HLA class II haplotypes in immunity is hampered by the lack of animal models expressing these genes as authentic cis-haplotypes. In this stuyd we describe transgenic expression of the autoimmune prone HLA DR3-DQ2 haplotype from a yearst artificial chromosome (YAC) containing an intact approx 320-kb region from HLA DRA to DQB2. In YAC-transgenic mice HLA DR and DQ gene products were expressed on B cells, macrophages, and dendritic cells, but not on T cells indicating cell-specific regulation. Positive selection of the CD5 compartment by human class II molecules was 67% efficient in YAC-homozygous mice lacking endogeneous class II molecules (A#beta#~nullull) and expressing only murine CD4. A broad range of TCR V#beta# families was used in the peripherla T cell repertoire, which was also purged of V#beta#5-, V#beta#11-, nad V#beta#12-bearing T cells by endogenous mouse mammary tumor virus-encoded superantigens. Expression of the HLA DR3-DQ2 haplotype on the A#beta#_nullull background was associated with normal CD8-dependent clearance of virus from influenze-infected mice and development of CD4- dependent protection from otherwise lethal infection with Salmonella typhimurium. HLA DR- and DQ-restricted T cell responses were also elicited following immunization with known T cell determinants presented by these molecules. These findings demonstrate the potential for human MHC class II haplotypes to function efficiently in transgenic mice and should provide valuable tools for developing humanized models of HMC-associated autoimmune diseases.