Abstract
[Background] Previously, we found that allograft-induced macrophages (AIM; H-2DbKb) were the major effector cells responsible for allograft (e.g., BALB/c skin and Meth A tumor; H-2DdKd) rejection. In the last meeting, we reported isolation of a cDNA, which encoded a novel receptor on AIM for allogeneic MHC (H-2Dd), by using anti-AIM monoclonal antibody (mAb; R15) and H-2Dd tetramer. We named this receptor "macrophage MHC receptor (MMR)". In the present study, we obtained a cDNA encoding a novel receptor on AIM for allogeneic MHC (H-2Kd). [Method] cDNA fragments were isolated by the T7 phage expression cloning method using R12 mAb and H-2Kd tetramer. Full length of the cDNA was obtained by the RACE method. mRNA expression was estimated by RT-PCR. cDNAs fused to GFP cDNA were transfected to HEK293T cells; and the binding of H-2 molecules to the transfectants was explored under a confocal microscope. The dissociation constant (Kd) of AIM toward H-2 molecules was assessed by flow cytometry. [Results] We isolated the full length (≈2.4kb) of cDNA, which encoded a receptor on AIM for allogeneic MHC (H-2Kd), and named the receptor 'MMR2'. The MMR2 mRNA was expressed exclusively in AIM but not in other cells infiltrating into allograft. HEK293 cells transfected with MMR2 cDNA reacted with H-2Kd, but not with other H-2, molecules. The H-2Kd binding was completely suppressed by R12 or anti-H-2Kd mAb. The Kd value of AIM toward H-2Kd was 2.8×10−9 M. [J Physiol Sci. 2006;56 Suppl:S121]
