RP105 is associated with MD-1 and transmits an activation signal in human B cells.
RP105 was originally discovered as a mouse B-cell surface molecule that transmits an activation signal. The signal leads to resistance against irradiation-induced apoptosis and massive B-cell proliferation. Recently, we found that mouse RP105 is associated with another molecule, MD-1. We have isolated here the human MD-1 cDNA. We show that human MD-1 is also associated with human RP105 and has an important role in cell surface expression of RP105. We also describe a monoclonal antibody (MoAb) that recognizes human RP105. Expression of RP105 is restricted to CD19(+) B cells. Histological studies showed that RP105 is expressed mainly on mature B cells in mantle zones. Germinal center cells are either dull or negative. RP105 is thus a novel human B-cell marker that is preferentially expressed on mature B cells. Moreover, the anti-RP105 MoAb activates B cells, leading to increases in cell size, expression of a costimulatory molecule CD80, and DNA synthesis. The B-cell activation pathway using RP105 is conserved in humans.
Miura
Y
Y
Department of Immunology and the Division of Dermatology in the Department of Internal Medicine, Saga Medical School, Saga, Japan.
Shimazu
R
R
Miyake
K
K
Akashi
S
S
Ogata
H
H
Yamashita
Y
Y
Narisawa
Y
Y
Kimoto
M
M
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD; D000954:Antigens, Surface / Q000276:immunology* / Q000378:metabolism; D001402:B-Lymphocytes / Q000276:immunology*; D001483:Base Sequence; D002645:Chickens; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D018858:Germinal Center / Q000276:immunology*; D006801:Humans; D008213:Lymphocyte Activation; D008223:Lymphoma / Q000473:pathology; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D014066:Palatine Tonsil / Q000166:cytology; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000276:immunology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013045:Species Specificity; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000954:Antigens, Surface; C092722:CD180 protein, human; D018076:DNA, Complementary; C115213:LY86 protein, human; C490500:Ly78 protein, mouse; C113553:Ly86 protein, mouse; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins