title: Apoptotic regulation of T cells and absence of immune deficiency in virus-infected gamma interferon receptor knockout mice.
abstract: Acute viral infections often induce a transient period of immune deficiency in which the host's T cells fail to proliferate in response to T-cell mitogens and fail to make an antigen-specific memory recall response. This has been associated with the enhanced sensitivity of these highly activated T cells to undergo apoptosis, or activation-induced cell death (AICD), upon T-cell receptor ligation. Here we show that gamma interferon receptor-deficient (IFN-gamma R-/-) mice mount a T-cell response to lymphocytic choriomeningitis virus (LCMV) infection but fail to undergo the transient immune deficiency. Instead, their T cells were hyperproliferative and relatively, but not completely, resistant to AICD. The immune response returned to homeostasis, but with delayed kinetics, in parallel with delayed clearance of the virus. Wild-type mice receiving high doses of disseminating LCMV Clone 13 are known to undergo clonal exhaustion of their virus-specific cytotoxic T lymphocytes (CTL). To determine whether this process was mediated by AICD associated with IFN-gamma or with Fas-Fas ligand interactions, LCMV-specific precursor CTL frequencies were examined in LCMV Clone 13-infected IFN-gamma R-/- or lpr (Fas-deficient) mice. In both instances, viral persistence was established and CTL precursors were greatly eliminated. This finding indicates that clonal exhaustion of CTL does not require IFN-gamma or Fas, even though both molecules influence AICD and the transient immune deficiency seen in the LCMV infection.
authors.affiliation: Department of Pathology, University of Massachusetts Medical Center, Worcester, Massachusetts 01655, USA.
authors.forename: B L
authors.initials: BL
authors.lastname: Lohman
authors.forename: R M
authors.initials: RM
authors.lastname: Welsh
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002455:Cell Division; D007371:Interferon-gamma / Q000378:metabolism; D008216:Lymphocytic Choriomeningitis / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D017471:Receptors, Interferon / Q000235:genetics* / Q000378:metabolism; D013154:Spleen / Q000276:immunology; D019014:fas Receptor / Q000235:genetics; D000096743:Interferon gamma Receptor
chemical_list: D007371:Interferon-gamma; D017471:Receptors, Interferon; D019014:fas Receptor; D000096743:Interferon gamma Receptor