Phenotypic, ultra-structural, and functional characterization of bovine peripheral blood dendritic cell subsets

• Published in: PloS one 2014-10, Vol.9 (10), p.e109273-e109273
• Main Authors: Sei, Janet J, Ochoa, Amanda S, Bishop, Elizabeth, Barlow, John W, Golde, William T
• Format: Article
• Language: English
• Subjects: Adaptive systems; Animal diseases; Animal sciences; Animals; Antigens; Biology and Life Sciences; Blood; Blood cells; Bovidae; Cattle; CD11c antigen; CD11c Antigen - metabolism; CD4 antigen; CD4 Antigens - metabolism; CD80 antigen; Cell activation; Cell surface; Cells, Cultured; Cytokines; Cytokines - metabolism; Degradation; Dendritic cells; Dendritic Cells - cytology; Dendritic Cells - drug effects; Dendritic Cells - metabolism; Dendritic structure; Endoplasmic reticulum; Flow Cytometry; Genotype & phenotype; Golgi apparatus; Immune response; Immune system; Immunology; Interferon; Internalization; Lymphocytes; Major histocompatibility complex; Medicine and Health Sciences; Microscopy, Electron, Transmission; Morphology; Nuclei; Nuclei (cytology); Oligodeoxyribonucleotides - pharmacology; Peripheral blood; Proteins; Real-Time Polymerase Chain Reaction; Structural analysis; Structure-function relationships; T cell receptors; Toll-like receptors; Tumor necrosis factor-α
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0109273

Dendritic cells (DC) are multi-functional cells that bridge the gap between innate and adaptive immune systems. In bovine, significant information is lacking on the precise identity and role of peripheral blood DC subsets. In this study, we identify and characterize bovine peripheral blood DC subsets directly ex vivo, without further in vitro manipulation. Multi-color flow cytometric analysis revealed that three DC subsets could be identified. Bovine plasmacytoid DC were phenotypically identified by a unique pattern of cell surface protein expression including CD4, exhibited an extensive endoplasmic reticulum and Golgi apparatus, efficiently internalized and degraded exogenous antigen, and were the only peripheral blood cells specialized in the production of type I IFN following activation with Toll-like receptor (TLR) agonists. Conventional DC were identified by expression of a different pattern of cell surface proteins including CD11c, MHC class II, and CD80, among others, the display of extensive dendritic protrusions on their plasma membrane, expression of very high levels of MHC class II and co-stimulatory molecules, efficient internalization and degradation of exogenous antigen, and ready production of detectable levels of TNF-alpha in response to TLR activation. Our investigations also revealed a third novel DC subset that may be a precursor of conventional DC that were MHC class II+ and CD11c-. These cells exhibited a smooth plasma membrane with a rounded nucleus, produced TNF-alpha in response to TLR-activation (albeit lower than CD11c+ DC), and were the least efficient in internalization/degradation of exogenous antigen. These studies define three bovine blood DC subsets with distinct phenotypic and functional characteristics which can be analyzed during immune responses to pathogens and vaccinations of cattle.