title: CD5 is dissociated from the B-cell receptor in B cells from bovine leukemia virus-infected, persistently lymphocytotic cattle: consequences to B-cell receptor-mediated apoptosis.
abstract: Bovine leukemia virus (BLV), a retrovirus related to human T-cell leukemia virus types 1 and 2, can induce persistent nonneoplastic expansion of the CD5(+) B-cell population, termed persistent lymphocytosis (PL). As in human CD5(+) B cells, we report here that CD5 was physically associated with the B-cell receptor (BCR) in normal bovine CD5(+) B cells. In contrast, in CD5(+) B cells from BLV-infected PL cattle, CD5 was dissociated from the BCR. In B cells from PL cattle, apoptosis decreased when cells were stimulated with antibody to surface immunoglobulin M (sIgM), while in B cells from uninfected cattle, apoptosis increased after sIgM stimulation. The functional significance of the CD5-BCR association was suggested by experimental dissociation of the CD5-BCR interaction by cross-linking of CD5. This caused CD5(+) B cells from uninfected animals to decrease apoptosis when stimulated with anti-sIgM. In contrast, in CD5(+) B cells from PL animals, in which CD5 was already dissociated from the BCR, there was no statistically significant change in apoptosis when CD5 was cross-linked and the cells were stimulated with anti-sIgM. Disruption of CD5-BCR interactions and subsequent decreased apoptosis and increased survival in antigenically stimulated B cells may be a mechanism of BLV-induced PL.
authors.affiliation: Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, Washington 99164-7040, USA. gcantor@vetmed.wsu.edu
authors.forename: G H
authors.initials: GH
authors.lastname: Cantor
authors.forename: S M
authors.initials: SM
authors.lastname: Pritchard
authors.forename: F
authors.initials: F
authors.lastname: Dequiedt
authors.forename: L
authors.initials: L
authors.lastname: Willems
authors.forename: R
authors.initials: R
authors.lastname: Kettmann
authors.forename: W C
authors.initials: WC
authors.lastname: Davis
mesh_terms: D000818:Animals; D017209:Apoptosis; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D018956:CD5 Antigens / Q000378:metabolism*; D002417:Cattle; D016583:Enzootic Bovine Leukosis / Q000276:immunology / Q000503:physiopathology / Q000821:virology*; D001909:Leukemia Virus, Bovine / Q000276:immunology*; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*
chemical_list: D018956:CD5 Antigens; D011947:Receptors, Antigen, B-Cell