title: Normal lymphocyte development but delayed humoral immune response in CD81-null mice.
abstract: CD81 is a cell surface molecule expressed on many cell types and associated with the CD19/CD21/Leu13 signal-transducing complex on B cells. A recent report implies that CD81 expression on thymic stromal cells is important in the maturation of thymocytes from CD4-CD8- to CD4+CD8+. However, we have produced CD81-null mice by gene targeting, and find that they undergo normal development of thymocytes and express normal numbers of T cells. B cells are also found in normal numbers in the spleen, blood, and peritoneal cavity of CD81-null mice, but they express a lower level of CD19 compared to heterozygous littermates. Finally, early antibody responses to the protein antigen ovalbumin are weaker in CD81-null mice compared to their heterozygous littermates. This is consistent with the proposed role of the CD19/CD21/CD81-signaling complex in lowering the threshold for B cell responses. These results show that CD81 is not required for maturation of T cells, but is important for optimal expression of CD19 on B cells and optimal stimulation of antibody production.
authors.affiliation: Department of Medicine and Oncology, Stanford University Medical Center, California 94305, USA.
authors.forename: H T
authors.initials: HT
authors.lastname: Maecker
authors.forename: S
authors.initials: S
authors.lastname: Levy
mesh_terms: D000818:Animals; D000917:Antibody Formation; D015703:Antigens, CD / Q000502:physiology*; D018941:Antigens, CD19 / Q000378:metabolism; D001402:B-Lymphocytes / Q000276:immunology*; D016516:CD4-CD8 Ratio; D005434:Flow Cytometry; D016130:Immunophenotyping; D008214:Lymphocytes / Q000166:cytology*; D008565:Membrane Proteins; D051379:Mice; D018345:Mice, Knockout; D013154:Spleen / Q000166:cytology; D060225:Tetraspanin 28; D013950:Thymus Gland / Q000166:cytology
chemical_list: D015703:Antigens, CD; D018941:Antigens, CD19; C554799:Cd81 protein, mouse; D008565:Membrane Proteins; D060225:Tetraspanin 28