CD5dim peripheral blood lymphocytes proliferate to exogenous IL-2 in the absence of antigen and kill in an NK-like manner.
Bovine CD5 lymphocytes can be categorized into "bright" and "dim" populations on the basis of CD5-specific monoclonal antibody (mAb) binding. CD5dim lymphocytes enriched by negative selection using mAbs to CD2 and MHC class II were examined phenotypically and functionally. CD5dim-enriched lymphocytes were 50-74% T19+ and 5-36% CD8+. Fewer than 13% expressed CD4, IgM, or MHC class II on their surface, and 6-20% expressed low levels of CD2. These cells did not proliferate to alloantigen or uv-inactivated BHV-1, but did proliferate to Con A and IL-2 in the absence of antigenic or mitogenic stimulation. Following IL-2 stimulation, the T19+ CD5dim lymphocytes proliferated and CD11c expression was induced. Freshly isolated CD5dim lymphocytes failed to kill in a bovine NK-like assay; however, following culture CD5dim-enriched lymphocytes exhibited non-MHC restricted cytotoxicity. We suggest that the CD5dim-enriched lymphocyte population contains the precursors of bovine LAK killing; however, a more extensive phenotype of these precursors in the bovine is yet to be determined.
Department of Veterinary Science, University of Wisconsin--Madison 53706.
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D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D000943:Antigens, Differentiation / Q000502:physiology*; D018956:CD5 Antigens; D002417:Cattle / Q000276:immunology*; D002469:Cell Separation; D003602:Cytotoxicity, Immunologic; D007376:Interleukin-2 / Q000502:physiology*; D007694:Killer Cells, Natural / Q000502:physiology; D008213:Lymphocyte Activation; D016131:Lymphocyte Subsets / Q000276:immunology / Q000502:physiology*; D010641:Phenotype
D000943:Antigens, Differentiation; D018956:CD5 Antigens; D007376:Interleukin-2