title: CD8+ T-cell dysfunction due to cytolytic granule deficiency in persistent Friend retrovirus infection.
abstract: Virus-specific CD8+ T cells are critical for the control of acute Friend virus (FV) infections, but are rendered impotent by CD4+ regulatory T cells during the chronic phase of infection. The current study examines this CD8+ T-cell dysfunction by analyzing the production and release of cytolytic molecules by CD8+ T cells. CD8+ T cells with an activated phenotype (CD43+) from acutely infected mice produced all three key components of lytic granules: perforin, granzyme A, and granzyme B. Furthermore, they displayed evidence of recent degranulation and in vivo cytotoxicity. In contrast, activated CD8+ T cells from chronically infected mice were deficient in cytolytic molecules and showed little evidence of recent degranulation and poor in vivo cytotoxicity. Evidence from tetramer-positive CD8+ T cells with known virus specificity confirmed the findings from the activated subset of CD8+ T cells. Interestingly, perforin and granzyme A mRNA levels were not significantly reduced during chronic infection, indicating control at a posttranscriptional level. Granzyme B deficiency was associated with a significant decrease in mRNA levels, but posttranscriptional control also appeared to contribute to deficiency. These results demonstrate a broad impairment of cytotoxic CD8+ T-cell effector function during chronic retroviral infection and explain the inability of virus-specific CD8+ T cells to eliminate persistent virus.
authors.affiliation: Institut fuer Virologie, Universitaetsklinikum Essen, 45122 Essen, Germany.
authors.forename: Gennadiy
authors.initials: G
authors.lastname: Zelinskyy
authors.forename: Shelly J
authors.initials: SJ
authors.lastname: Robertson
authors.forename: Simone
authors.initials: S
authors.lastname: Schimmer
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Messer
authors.forename: Kim J
authors.initials: KJ
authors.lastname: Hasenkrug
authors.forename: Ulf
authors.initials: U
authors.lastname: Dittmer
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D015550:Cell Degranulation; D003602:Cytotoxicity, Immunologic; D005260:Female; D005622:Friend murine leukemia virus / Q000276:immunology*; D053804:Granzymes; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D012697:Serine Endopeptidases / Q000502:physiology*
chemical_list: D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin; D053804:Granzymes; C509214:Gzmb protein, mouse; D012697:Serine Endopeptidases