Identity of human Lyb-2 and CD72 and localization of the gene to chromosome 9.
We have recently reported the isolation of cDNA clones encoding the human homolog of the mouse B cell differentiation antigen Lyb-2. Expression of Lyb-2 is restricted to B lineage cells and turned off in antibody-secreting plasma cells in both mice and humans. Functional studies with anti-mouse Lyb-2 monoclonal antibodies (mAb) suggest that this protein may be involved in signals for B cell proliferation. We now describe the generation of mAb specific for human Lyb-2. Furthermore, we demonstrate that the human Lyb-2 protein is recognized by a mAb specific for the newly clustered pan B cell surface antigen CD72, which had been defined by mAb. Mouse L(tk-) cells expressing a transfected cDNA encoding human Lyb-2 bind a mAb specific for CD72. We further show that an antiserum and a mAb specific for human Lyb-2 and an anti-CD72 mAb immunoprecipitate the identical protein from human splenic B cells and B cell lines, as well as from transfected L(tk-) cells. These data indicate that CD72 is the human equivalent of mouse Lyb-2. We have additionally localized the gene for human Lyb-2/CD72 on the short arm of chromosome 9. Mouse Lyb-2 had been previously mapped to mouse chromosome 4. Lyb-2/CD72 is now the tenth gene known to be localized on human chromosome 9 and mouse chromosome 4.
Von Hoegen
I
I
Department of Medicine, Stanford University Medical Center, CA 94305.
Hsieh
C L
CL
Scharting
R
R
Francke
U
U
Parnes
J R
JR
D000818:Animals; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000032:analysis*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000032:analysis* / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D002874:Chromosome Mapping; D002899:Chromosomes, Human, Pair 9; D006801:Humans; D007739:L Cells / Q000276:immunology; D051379:Mice; D008809:Mice, Inbred C3H; D014162:Transfection
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; C064228:CD72 protein, human