title: Differential regulation of primary and secondary CD8+ T cells in the central nervous system.
abstract: T cell accumulation and effector function following CNS infection is limited by a paucity of Ag presentation and inhibitory factors characteristic of the CNS environment. Differential susceptibilities of primary and recall CD8+ T cell responses to the inhibitory CNS environment were monitored in naive and CD8+ T cell-immune mice challenged with a neurotropic coronavirus. Accelerated virus clearance and limited spread in immunized mice was associated with a rapid and increased CNS influx of virus-specific secondary CD8+ T cells. CNS-derived secondary CD8+ T cells exhibited increased cytolytic activity and IFN-gamma expression per cell compared with primary CD8+ T cells. However, both Ag-specific primary and secondary CD8+ T cells demonstrated similar contraction rates. Thus, CNS persistence of increased numbers of secondary CD8+ T cells reflected differences in the initial pool size during peak inflammation rather than enhanced survival. Unlike primary CD8+ T cells, persisting secondary CD8+ T cells retained ex vivo cytolytic activity and expressed high levels of IFN-gamma following Ag stimulation. However, both primary and secondary CD8+ T cells exhibited reduced capacity to produce TNF-alpha, differentiating them from effector memory T cells. Activation of primary and secondary CD8+ T cells in the same host using adoptive transfers confirmed similar survival, but enhanced and prolonged effector function of secondary CD8+ T cells in the CNS. These data suggest that an instructional program intrinsic to T cell differentiation, rather than Ag load or factors in the inflamed CNS, prominently regulate CD8+ T cell function.
authors.affiliation: Department of Neurology, Keck School of Medicine, University of Southern California, 1333 San Pablo Street, Los Angeles, CA 90033, USA.
authors.forename: Chandran
authors.initials: C
authors.lastname: Ramakrishna
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Stohlman
authors.forename: Roscoe A
authors.initials: RA
authors.lastname: Atkinson
authors.forename: David R
authors.initials: DR
authors.lastname: Hinton
authors.forename: Cornelia C
authors.initials: CC
authors.lastname: Bergmann
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000473:pathology / Q000821:virology; D002465:Cell Movement / Q000276:immunology; D002470:Cell Survival / Q000276:immunology; D002490:Central Nervous System / Q000276:immunology* / Q000378:metabolism / Q000473:pathology* / Q000821:virology; D018352:Coronavirus Infections / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D004660:Encephalitis / Q000276:immunology; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D005260:Female; D007156:Immunologic Memory; D007371:Interferon-gamma / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D006517:Murine hepatitis virus / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism / Q000473:pathology / Q000821:virology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology / Q000378:metabolism / Q000473:pathology / Q000821:virology
chemical_list: D018984:Epitopes, T-Lymphocyte; D007371:Interferon-gamma