The Protozoan Neospora Caninum Directly Triggers Bovine Nk Cells to Produce Gamma Interferon and to Kill Infected Fibroblasts.
From: Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, P.O. Box 8146 Dep., N-0033 Oslo, Norway.
Infection and immunity
- Publish Date: Feb 2006
- ISSN: 0019-9567
- Volume: 74
- Issue: 2
- Pages: 953-60
- Medium: Print
- Language: English
- Citation (JAMA): Boysen Preben, Klevar Siv, Olsen Ingrid, et al. The Protozoan Neospora Caninum Directly Triggers Bovine Nk Cells to Produce Gamma Interferon and to Kill Infected Fibroblasts.. Infect. Immun. Feb 2006;74:953-60
Abstract
Natural killer (NK) cells are considered to be key players in the early innate responses to protozoan infections, primarily indirectly by producing gamma interferon (IFN-gamma) in response to cytokines, like interleukin 12 (IL-12). We demonstrate that live, as well as heat-inactivated, tachyzoites of Neospora caninum, a Toxoplasma-like protozoan, directly trigger production of IFN-gamma from purified, IL-2-activated bovine NK cells. This response occurred independently of IL-12 but was increased by the addition of the cytokine. A similar IFN-gamma response was measured in cocultures of NK cells and N. caninum-infected autologous fibroblasts. However, no NK cell-derived IFN-gamma response was detected when cells were cultured with soluble antigens from the organism, indicating that intact tachyzoites or nonsoluble components are necessary for NK cell triggering. Furthermore, N. caninum-infected autologous fibroblasts had increased susceptibility to NK cell cytotoxicity compared to uninfected fibroblasts. This cytotoxicity was largely mediated by a perforin-mediated mechanism. The activating receptor NKp46 was involved in cytotoxicity against fibroblasts but could not explain the increased cytotoxicity against infected targets. Interestingly, N. caninum tachyzoites were able to infect cultured NK cells, in which tachyzoites proliferated inside parasitophorous vacuoles. Together, these findings underscore the role of NK cells as primary responders during a protozoan infection, describe intracellular protozoan infection of NK cells in vitro for the first time, and represent the first functional study of purified bovine NK cells in response to infection.
Mesh Headings (Keywords): Animals, Cattle, Cells, Cultured, Coccidiosis, Coculture Techniques, Cytotoxicity, Immunologic, Fibroblasts, Immunity, Natural, Interferon Type II, Killer Cells, Natural, Male, Neospora
Check for Full Text / PubMed Unique Identifier (PMID): 16428740
This abstract is part of PubMed, a service of the U.S. National Library of Medicine. PubMed includes more than 17 million citations from MEDLINE and other life science journals for biomedical articles. See Copyright and Disclaimers.
Linked medical terms appearing on this page are added by Healia to help readers find more information and are not part of the original PubMed document.
The data herein was last updated on July 8th, 2008 and may not reflect the most current and accurate data available from NLM.