Screening of mouse embryonic stem (ES) cells lacking macrophage MHC (H-2K^d) receptor 2

Abstract

We reported previously that allograft-induced macrophages (AIM) in C57BL/6 (H-2D^bK^b) mice were essential for the rejection of H-2D^dK^d allografts including BALB/c skin and Meth A tumor. Recently, we isolated a cDNA encoding a novel receptor on AIM for the H-2K^d molecule by the expression cloning method using an anti-AIM monoclonal antibody (R12) and H-2K^d tetramer and named it macrophage MHC receptor 2 (MMR2). To know the physiological roles of MMR2, we are trying to generate mouse strains deficient in MMR2 by homologous recombination. In the present study, a targeting plasmid containing a neomycin (neo^r) /thymidine kinase cassette in the MMR2 locus was constructed using genomic DNA fragments derived from Sv129 mouse strain; and the targeting plasmid was introduced into mouse ES cells. To detect homologous recombination and the presence of the neo^r allele, 168 ES clones were screened by PCR analysis of genomic DNA. Among them 4 clones were detected as homologous recombination products in the 3′ locus of MMR2 gene. The recombination of 5′ locus is under investigation. [J Physiol Sci. 2008;58 Suppl:S202]