title: HLA-B62 as a possible ligand for the human homologue of mouse macrophage MHC receptor 2 (MMR2) on monocytes.
abstract: We previously reported that a population of allograft (H-2D(d)K(d))-induced macrophages (AIM) in C57BL/6 (H-2D(b)K(b)) mice exhibited major histocompatibility complex (MHC) haplotype (H-2D(d) or H-2K(d))-specific killing of allografts in a macrophage MHC receptor 1 or 2 (MMR1 or 2)-dependent manner. In the present study, we isolated a cDNA encoding a human homologue (83.6% amino-acid identity) of mouse MMR2 from a human cDNA library, the donors of which had never been allografted. The cDNA (2376-bp) encoded a 791-amino-acid polypeptide with a calculated molecular mass of 91kDa. Unexpectedly, the mRNA was expressed at least in part in peripheral blood mononuclear cells (PBMCs) or monocytes, but not in granulocytes or lymphocytes. The expression varied from volunteer to volunteer: PBMCs from 8 volunteers expressed human MMR2 at similar levels, whereas those from 8 other volunteers showed no or much less expression of it. Flow cytometric analyses revealed that HEK293T cells expressing human MMR2 protein bound fluorescein-labeled HLA-B62, but not A2, A-11, A-24 or B7, with a dissociation constant (=8.9x10(-9)M) and that the interaction was completely inhibited by the addition of R12 mAb specific for mouse MMR2. Similarly, the expression of mouse MMR2 varied from strain to strain in mice: PBMCs from 9 non-H-2K(d), but not from 3 H-2K(d), mice expressed mouse MMR2 specific for H-2K(d). These results suggest that human MMR2 on monocytes may be a novel receptor for HLA-B62.
authors.affiliation: Department of Physiology, Osaka Medical College, Takatsuki, Osaka-fu 569-8686, Japan.
authors.forename: Tetsunosuke
authors.initials: T
authors.lastname: Shimizu
authors.forename: Junko
authors.initials: J
authors.lastname: Tashiro-Yamaji
authors.forename: Michihiro
authors.initials: M
authors.lastname: Hayashi
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Inoue
authors.forename: Minenori
authors.initials: M
authors.lastname: Ibata
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kubota
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Tanigawa
authors.forename: Ryotaro
authors.initials: R
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D002460:Cell Line; D015723:Gene Library; D015235:HLA-B Antigens / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D015235:HLA-B Antigens; D008024:Ligands; C516324:MMR2 protein, mouse; D011971:Receptors, Immunologic