Tashiro-Yamaji Junko, Einaga-Naito Kuniko, Kubota Takahiro, Yoshida Ryotaro
Department of Physiology, Osaka Medical College, Japan.
Microbiol Immunol. 2006;50(2):105-16. doi: 10.1111/j.1348-0421.2006.tb03775.x.
The generation of knockout mice demonstrated that noncytotoxic CD4(+), but not cytotoxic CD8(+), T cells were essential for the rejection of skin or organ allografts. Earlier we reported that allograftinduced macrophages (AIM) in mice lysed allografts with H-2 haplotype specificity, implying screening of grafts by AIM. Here, we isolated a cDNA clone encoding a novel receptor on AIM (H-2D(b)) for an allogeneic major histocompatibility complex (MHC) class I molecule, H-2D(d), by using H-2D(d) tetramer and a monoclonal antibody (mAb; R15) specific for AIM. The cDNA (1,181-bp) encoded a 342-amino acid polypeptide with a calculated molecular mass of 45 kDa and was found to be expressed on AIM, but not on resident macrophages or other cells, infiltrating into the rejection site. HEK293T cells transfected with this cDNA reacted with R15 mAb and H-2D(d), but not H-2L(d), H-2K(d), H-2D(b), H-2K(b), H-2D(k), or H-2K(k), molecules; and the H-2D(d) binding was suppressed by the addition of R15 or anti-H-2D(d) mAb. AIM yielded a specific saturation isotherm in the presence of increasing concentrations of H-2D(d), but not H-2D(b) or H-2D(k), molecules. The dissociation constant of AIM toward H-2D(d) tetramers was 1.9 x 10(-9) M ; and the binding was completely inhibited by the addition of R15 or anti-H-2D(d) mAb. These results reveal that a novel receptor for an allogeneic H-2D(d) molecule was induced on effector macrophages responsible for allograft (H-2(d)) rejection in H-2(b) mice.
基因敲除小鼠的产生表明，无细胞毒性的CD4(+)而非有细胞毒性的CD8(+) T细胞对于皮肤或器官异体移植的排斥至关重要。此前我们报道，小鼠体内的移植诱导巨噬细胞（AIM）能以H-2单倍型特异性裂解异体移植物，这意味着AIM对移植物进行了筛选。在此，我们通过使用H-2D(d)四聚体和针对AIM的单克隆抗体（mAb；R15），分离出一个编码AIM（H-2D(b)）上一种新型受体的cDNA克隆，该受体针对同种异体主要组织相容性复合体（MHC）I类分子H-2D(d)。该cDNA（1181 bp）编码一个342个氨基酸的多肽，计算分子量为45 kDa，发现其在AIM上表达，但在驻留巨噬细胞或浸润到排斥部位的其他细胞上不表达。用该cDNA转染的HEK293T细胞与R15 mAb和H-2D(d)反应，但不与H-2L(d)、H-2K(d)、H-2D(b)、H-2K(b)、H-2D(k)或H-2K(k)分子反应；并且通过添加R15或抗H-2D(d) mAb可抑制H-2D(d)的结合。在存在浓度不断增加的H-2D(d)分子但不存在H-2D(b)或H-2D(k)分子的情况下，AIM产生了特异性饱和等温线。AIM对H-2D(d)四聚体的解离常数为1.9×10(-9) M；并且通过添加R15或抗H-2D(d) mAb可完全抑制结合。这些结果表明，在负责H-2(b)小鼠异体移植（H-2(d)）排斥的效应巨噬细胞上诱导出了一种针对同种异体H-2D(d)分子的新型受体。
