A Role for Perforin in Downregulating T-Cell Responses during Chronic Viral Infection. Matloubian, M., Suresh, M., Glass, A., Galvan, M., Chow, K., Whitmire, J. K., Walsh, C. M., Clark, W. R., & Ahmed, R. Journal of Virology, 73(3):2527–2536, March, 1999.
A Role for Perforin in Downregulating T-Cell Responses during Chronic Viral Infection [link]Paper  abstract   bibtex   
Cytotoxic T cells secrete perforin to kill virus-infected cells. In this study we show that perforin also plays a role in immune regulation. Perforin-deficient (perf −/−) mice chronically infected with lymphocytic choriomeningitis virus (LCMV) contained greater numbers of antiviral T cells compared to persistently infected +/+ mice. The enhanced expansion was seen in both CD4 and CD8 T cells, but the most striking difference was in the numbers of LCMV-specific CD8 T cells present in infected perf −/− mice. Persistent LCMV infection of +/+ mice results in both deletion and anergy of antigen-specific CD8 T cells, and our results show that this peripheral “exhaustion” of activated CD8 T cells occurred less efficiently in perf −/− mice. This excessive accumulation of activated CD8 T cells resulted in immune-mediated damage in persistently infected perf −/− mice; ∼50% of these mice died within 2 to 4 weeks, and mortality was fully reversed by in vivo depletion of CD8 T cells. This finding highlights an interesting dichotomy between the role of perforin in viral clearance and immunopathology; perforin-deficient CD8 T cells were unable to clear the LCMV infection but were capable of causing immune-mediated damage. Finally, this study shows that perforin also plays a role in regulating T-cell-mediated autoimmunity. Mice that were deficient in both perforin and Fas exhibited a striking acceleration of the spontaneous lymphoproliferative disease seen in Fas-deficient (lpr) mice. Taken together, these results show that the perforin-mediated pathway is involved in downregulating T-cell responses during chronic viral infection and autoimmunity and that perforin and Fas act independently as negative regulators of activated T cells.
@article{matloubian_role_1999,
	title = {A {Role} for {Perforin} in {Downregulating} {T}-{Cell} {Responses} during {Chronic} {Viral} {Infection}},
	volume = {73},
	issn = {0022-538X},
	url = {https://www.ncbi.nlm.nih.gov/pmc/articles/PMC104500/},
	abstract = {Cytotoxic T cells secrete perforin to kill virus-infected cells. In this study we show that perforin also plays a role in immune regulation. Perforin-deficient (perf −/−) mice chronically infected with lymphocytic choriomeningitis virus (LCMV) contained greater numbers of antiviral T cells compared to persistently infected +/+ mice. The enhanced expansion was seen in both CD4 and CD8 T cells, but the most striking difference was in the numbers of LCMV-specific CD8 T cells present in infected perf −/− mice. Persistent LCMV infection of +/+ mice results in both deletion and anergy of antigen-specific CD8 T cells, and our results show that this peripheral “exhaustion” of activated CD8 T cells occurred less efficiently in perf −/− mice. This excessive accumulation of activated CD8 T cells resulted in immune-mediated damage in persistently infected perf −/− mice; ∼50\% of these mice died within 2 to 4 weeks, and mortality was fully reversed by in vivo depletion of CD8 T cells. This finding highlights an interesting dichotomy between the role of perforin in viral clearance and immunopathology; perforin-deficient CD8 T cells were unable to clear the LCMV infection but were capable of causing immune-mediated damage. Finally, this study shows that perforin also plays a role in regulating T-cell-mediated autoimmunity. Mice that were deficient in both perforin and Fas exhibited a striking acceleration of the spontaneous lymphoproliferative disease seen in Fas-deficient (lpr) mice. Taken together, these results show that the perforin-mediated pathway is involved in downregulating T-cell responses during chronic viral infection and autoimmunity and that perforin and Fas act independently as negative regulators of activated T cells.},
	number = {3},
	urldate = {2024-06-25},
	journal = {Journal of Virology},
	author = {Matloubian, Mehrdad and Suresh, M. and Glass, Alison and Galvan, Marisa and Chow, Kit and Whitmire, Jason K. and Walsh, Craig M. and Clark, William R. and Ahmed, Rafi},
	month = mar,
	year = {1999},
	pmid = {9971838},
	pmcid = {PMC104500},
	pages = {2527--2536},
}

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