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Published on: May 6, 2019
Cutting edge: viral infection breaks NK cell tolerance to "missing self"
1Department of Microbiology and Immunology and the Cancer Research Institute, University of California, San Francisco, CA 94143, USA.
Natural killer (NK) cells normally tolerate cells lacking MHC class I. However, infection can break this tolerance, leading to NK cell rejection of these "missing self" cells.
Area of Science:
- Immunology
- Cellular Biology
- Infectious Disease
Background:
- Natural killer (NK) cells are crucial for innate immunity, primarily targeting cells lacking MHC class I expression.
- MHC class I-deficient cells are typically tolerated by NK cells, a phenomenon known as
Purpose of the Study:
- To investigate the impact of MHC class I absence on NK cell phenotype and function.
- To determine how NK cell tolerance to MHC class I-deficient cells is established and maintained.
- To explore the role of infection in breaking NK cell self-tolerance.
Main Methods:
- Comparison of NK cell characteristics in beta(2)-microglobulin-deficient (B2m(-/-)) and wild-type mice.
- Analysis of NK cell responses in mixed wild-type:B2m(-/-) chimeric mice.
- Assessment of NK cell tolerance and rejection following mouse cytomegalovirus (MCMV) infection.
Main Results:
- NK cells from B2m(-/-) and wild-type mice showed similar phenotypic and functional profiles.
- Both B2m(-/-) and wild-type NK cells proliferated and produced IFN-gamma upon MCMV infection.
- Initial tolerance of NK cells to MHC class I-deficient cells in chimeras was lost over time and rapidly broken by MCMV infection, leading to rejection of B2m(-/-) hematopoietic cells.
Conclusions:
- NK cells can maintain tolerance to "missing self" targets under normal conditions.
- Acute inflammation induced by infection can overcome established NK cell self-tolerance.
- NK cell-mediated rejection of MHC class I-deficient cells can occur rapidly during infection.
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