Antigen amount dictates CD8+ T-cell exhaustion during chronic viral infection irrespective of the type of antigen presenting cell

Authors


Full correspondence: Prof. Annette Oxenius, Institute of Microbiology, Wolfgang-Pauli-Str. 10, HCI G401, 8093 Zurich, Switzerland

Fax: +41-44-632-10-98

e-mail: oxenius@micro.biol.ethz.ch

See accompanying Commentary:

http://dx.doi.org/10.1002/eji.201242852

Abstract

Chronic viral infections lead to CD8+ T-cell exhaustion, characterized by impaired cytokine secretion and loss of proliferative capacity. While viral load and T-cell dysfunction correlate, it is currently unclear whether the quality of a cell type presenting antigen determines the degree of T-cell exhaustion or if the overall amount of antigen recognized by T cells promotes exhaustion. We found that chronic lymphocytic chorio-meningitis virus infection led to decreased CD8+ T-cell exhaustion in DC-MHC class I (MHCI) mice, in which CD8+ T cells can only recognize antigen on DCs. However, this increase in CD8+ T-cell function came at the expense of fatal immunopathology. Additional antigen recognition on nonhematopoietic cells in DC-MHCI mice promoted T-cell exhaustion and avoidance of immunopathology. Likewise, increased numbers of antigen-expressing hematopoietic cells, as well as a selective elevation of the number of DCs as the only cell type presenting antigen in DC-MHCI mice, resulted in compromised T-cell function. These results favor a scenario in which the overall amount of antigen exposure, rather than the type of cell engaging with virus-specific CD8+ T cells, is responsible for their functional exhaustion. Furthermore, exhaustion of virus-specific CD8+ T cells leads to avoidance of life-threatening immunopathology.

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