Biochemical identity of the mouse Ly-19.2 and Ly-32.2 alloantigens with the B cell differentiation antigen Lyb-2/CD72.
Lyb-2/CD72 is a 45-kDa mouse B cell surface protein that binds CD5 (Ly-1) and has been shown to induce B cell proliferation upon mAb binding. The serologically defined Ly-19.2 and Ly-32.2 lymphocyte alloantigens have mouse strain distribution patterns similar to that of the Lyb-2/CD72 alleles and map to the same region on chromosome 4 as Lyb-2/CD72. Our recent isolation of the Lyb-2a, -2b, and -2c cDNA has enabled us in this report to examine the relationship between Ly-19, Ly-32, and Lyb-2/CD72. A rat T cell line transfected with a mouse Lyb-2a cDNA is recognized by Ly-19.2-specific mAb, whereas transfectants expressing the Lyb-2b cDNA are recognized by both Ly-19.2 and Ly-32.2-specific mAb. Cell surface iodination immunoprecipitation analysis from Lyb-2a cDNA transfectants using Lyb-2a- and Ly-19.2-specific mAb as well as from Lyb-2b cDNA transfectants using Lyb-2b-, Ly-19.2-, and Ly-32.2-specific Ab, produced immunoprecipitates containing comigrating 45-kDa polypeptides. Preclearing studies with these transfectants indicate that the immunoprecipitated proteins represent the same polypeptide chain. These results demonstrate that the mouse Ly-19.2 and Ly-32.2 alloantigens are in fact the B cell differentiation Ag Lyb-2/CD72.
Robinson
W H
WH
Department of Medicine, Stanford University School of Medicine, CA 94305.
Landolfi
M M
MM
Schäfer
H
H
Parnes
J R
JR
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD / Q000032:analysis* / Q000235:genetics / Q000276:immunology; D000944:Antigens, Differentiation, B-Lymphocyte / Q000032:analysis* / Q000235:genetics / Q000276:immunology; D000950:Antigens, Ly / Q000032:analysis* / Q000276:immunology; D002460:Cell Line; D007519:Isoantigens / Q000032:analysis* / Q000276:immunology; D051379:Mice; D011233:Precipitin Tests; D051381:Rats; D014162:Transfection
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D000950:Antigens, Ly; C064228:CD72 protein, human; D007519:Isoantigens