title: Mac-1-negative B-1b phenotype of natural antibody-producing cells, including those responding to Gal alpha 1,3Gal epitopes in alpha 1,3-galactosyltransferase-deficient mice.
abstract: Human natural Abs against Galalpha1-3Galbeta1-4GlcNAc (Gal) epitopes are a major barrier to xenotransplantation. Studies in this report, which use combined multiparameter flow cytometric sorting and enzyme-linked immunospot assay, demonstrate that anti-Gal IgM-producing cells are found exclusively in a small B cell subpopulation (i.e., CD21(-/low) IgM(high) B220(low) CD5(-) Mac-1(-) 493(-) cells) in the spleens of alpha1, 3-galactosyltransferase-deficient mice. All IgM-producing cells were detected in a similar splenic subpopulation of alpha1, 3-galactosyltransferase-deficient and wild-type mice. A higher frequency of B cells with anti-Gal surface IgM receptors was observed in the peritoneal cavity than in the spleen, but these did not actively secrete Abs, and showed phenotypic properties of B-1b cells (CD21(-/low) IgM(high) CD5(-) CD43(+) Mac-1(+)). However, these became Mac-1(-) and developed anti-Gal Ab-producing activity after in vitro culture with LPS. The splenic B cells with anti-Gal receptors consisted of both Mac-1(+) B-1b cells and Mac-1(-) B-1b-like cells. The latter comprised most anti-Gal IgM-producing cells. Our studies indicate that anti-Gal natural IgM Abs are produced by a B1b-like, Mac-1(-) splenic B cell population and not by plasma cells or B-1a cells. They are consistent with a model whereby B-1b cells lose Mac-1 expression upon Ag exposure and that these, rather than plasma cells, become the major IgM Ab-producing cell population.
authors.affiliation: Transplantation Biology Research Center, Surgical Service, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02129, USA.
authors.forename: H
authors.initials: H
authors.lastname: Ohdan
authors.forename: K G
authors.initials: KG
authors.lastname: Swenson
authors.forename: H S
authors.initials: HS
authors.lastname: Kruger Gray
authors.forename: Y G
authors.initials: YG
authors.lastname: Yang
authors.forename: Y
authors.initials: Y
authors.lastname: Xu
authors.forename: A D
authors.initials: AD
authors.lastname: Thall
authors.forename: M
authors.initials: M
authors.lastname: Sykes
mesh_terms: D000818:Animals; D000921:Antibody-Producing Cells / Q000201:enzymology / Q000276:immunology / Q000378:metabolism; D016175:B-Lymphocyte Subsets / Q000201:enzymology* / Q000276:immunology* / Q000378:metabolism; D018956:CD5 Antigens / Q000378:metabolism; D004187:Disaccharides / Q000276:immunology* / Q000378:metabolism; D018985:Epitopes, B-Lymphocyte / Q000276:immunology* / Q000378:metabolism; D005700:Galactosyltransferases / Q000172:deficiency* / Q000235:genetics*; D007111:Immunity, Cellular; D007075:Immunoglobulin M / Q000096:biosynthesis; D016130:Immunophenotyping; D017493:Leukocyte Common Antigens / Q000096:biosynthesis; D016177:Macrophage-1 Antigen / Q000096:biosynthesis* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010529:Peritoneal Cavity / Q000166:cytology; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism; D017464:Receptors, Complement 3d / Q000096:biosynthesis; D013154:Spleen / Q000166:cytology / Q000201:enzymology / Q000276:immunology
chemical_list: D018956:CD5 Antigens; D004187:Disaccharides; D018985:Epitopes, B-Lymphocyte; D007075:Immunoglobulin M; D016177:Macrophage-1 Antigen; D011947:Receptors, Antigen, B-Cell; D017464:Receptors, Complement 3d; C055075:galactosyl-(1-3)galactose; D005700:Galactosyltransferases; D017493:Leukocyte Common Antigens