Phenotypic and functional characterization of bovine immune cells modulated by staphylococcal enterotoxin C1


Seo, Keun Seok.. (2007). Phenotypic and functional characterization of bovine immune cells modulated by staphylococcal enterotoxin C1. Theses and Dissertations Collection, University of Idaho Library Digital Collections.

Phenotypic and functional characterization of bovine immune cells modulated by staphylococcal enterotoxin C1
Seo, Keun Seok.
Superantigens Staphylococcus aureus infections--Prevention Cattle--Diseases--Genetic aspects
Microbiology, Molecular Biology, and Biochemistry
Superantigens (SAgs) induce aberrant activation of T cells and antigen presenting cells (APCs), resulting in extensive T cell proliferation, anergy, immunosuppression, and acute inflammation. It has been postulated that chronic staphylococcal infections are exacerbated by Sag-induced immune dysfunction. Though important, there is limited information describing the effects of SAgs on APCs and T cells in species other than human and mice. To extend our understanding of the immunopathological role of SAgs on the bovine immune system, bovine peripheral blood mononuclear cells were exposed in vitro, to a relatively low dose (5 ng/ml) of staphylococcal enterotoxin C1 (SEC1) for up to 10 days. Long-term exposure to SEC1 caused T cells to proliferate, but proliferation of CD8 T cells occurred more vigorously. Transcription of Foxp3, CD152, IL-10, and TGF-[Beta] in CD4CD25{esc}p+{esc}s T cells increased dramatically, while that of IL-2 returned to basal level. Functional studies demonstrating that the proliferation of naïve peripheral blood mononuclear cells in response to heat-killed-fixed S. aureus is partially suppressed by IL-10 and TGF-[Beta], provides evidence that these cells are phenotypically and functionally analogous to regulatory T cell. Following exposure to SEC1, the phenotype and morphology of APCs was CD14 low, MHC IIhigh, CD11alow, CD11bhigh, CD11chigh, and CD1ahigh with numerous fine dendrites on the cell surface, and are typical characteristics of dendritic cells (DCs) described in human and other animals. Transcriptional analysis of selected cytokines and chemokines showed that the transcription of TNF-[alpha], CCL3, CCL8, and CXCL12, involved in mononuclear cell migration, increased and remained elevated, while others increased but gradually decreased. Consistent with these data, in vitro cell migration assays revealed granulocyte migration followed by mononuclear cell migration. An autologous mixed leukocyte reaction showed that SEC1-derived DCs induced spontaneous dose-dependent proliferation of naïve T cells. The proliferation in CD8{esc}p+{esc}s T cells was more vigorous than that of CD4{esc}p+{esc}s T cells. These results suggest that SAgs induce a unique phenotypic and functional immunomodulation of bovine APCs and T cells. Importantly, these studies provide further insight on the immunopathological role of SAgs in S. aureus bovine mastitis through in vitro analysis.
Thesis (Ph. D., Microbiology, Molecular Biology, and Biochemistry)--University of Idaho, July 2007.
Major Professor:
Gregory A. Bohach.
Defense Date:
July 2007.
Format Original:
x, 111 leaves :ill. (some col.) ;29 cm.

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