title: Differential expression of CD5 on B lymphocytes in cattle infected with Mycobacterium avium subsp. paratuberculosis.
abstract: CD5 is a cell surface molecule involved in antigen recognition and is present on all T lymphocytes and a subset of B lymphocytes. The purpose of this study was to examine CD5+ expression on peripheral blood B cells from healthy, noninfected cattle and cattle with subclinical and clinical paratuberculosis. Peripheral blood mononuclear cells (PBMC) were freshly isolated or cultured for 7 days in the presence or absence of live Mycobacterium avium subsp. paratuberculosis (M. avium subsp. paratuberculosis), and then analyzed by flow cytometry for CD5 expression within the B cell subpopulation. Analysis demonstrated a significant increase (P<0.01) in B cells in clinical animals as compared to healthy control cows and subclinically infected cows. In addition, three subpopulations within the CD5+ B cell population were identified: CD5dim, CD5bright, and a minor population that was characterized as CD5extra bright. A decrease in the CD5dim B cell population along with a concomitant increase in CD5bright B cells was observed in infected cows, an effect that was highly significant (P<0.01) for subclinically infected cows in cultured PBMC. In vitro infection with live M. avium subsp. paratuberculosis did not affect CD5+ expression patterns on B cells, regardless of animal infection status. Addition of exogenous IL-10 to PBMC cultures resulted in decreased numbers of CD5(bright) B cells for healthy control cows, whereas, a synergistic effect of IL-10 and infection with live M. avium subsp. paratuberculosis resulted in increased CD5bright B cells for subclinically infected cows. These results suggest that differential expression of CD5bright and CD5dim subpopulations on B cells in animals with paratuberculosis may reflect a shift in host immunity during the disease process.
authors.affiliation: USDA-ARS, National Animal Disease Center, Bacterial Diseases of Livestock Research Unit, 2300 Dayton Road, Ames, IA 50010, United States. judy.stabel@ars.usda.gov
authors.forename: J R
authors.initials: JR
authors.lastname: Stabel
authors.forename: M S
authors.initials: MS
authors.lastname: Khalifeh
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D018956:CD5 Antigens / Q000276:immunology*; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology* / Q000382:microbiology*; D005434:Flow Cytometry / Q000662:veterinary; D016927:Mycobacterium avium subsp. paratuberculosis / Q000276:immunology*; D010283:Paratuberculosis / Q000276:immunology*
chemical_list: D018956:CD5 Antigens