title: Subsets of memory cytotoxic T lymphocytes elicited by vaccination influence the efficiency of secondary expansion in vivo.
abstract: Vaccine-elicited cytotoxic T lymphocytes (CTL) should be long-lived memory cells that can rapidly expand in number following re-exposure to antigen. The present studies were initiated to analyze the ability of plasmid interleukin-12 (IL-12) to augment CTL responses in mice when delivered during the peak phase of an immune response elicited by a plasmid human immunodeficiency virus type 1 gp120 DNA vaccine. Delivery of plasmid IL-12 on day 10 postimmunization resulted in a robust expansion of gp120-specific CD8+ T cells, as measured by tetramer, gamma interferon ELISPOT, and functional-killing assays. Interestingly, this delayed administration of plasmid IL-12 had no significant effect on antigen-specific CD4(+)-T-cell and antibody responses. Phenotypic analyses suggested that administration of plasmid IL-12 near the time of the peak CTL response activated and expanded antigen-specific effector cells, preventing their loss through apoptosis. However, this IL-12-augmented population of gp120-specific CD8+ T cells did not efficiently expand following gp120 boost immunization, suggesting that these effector cells would be of little utility in expanding to contain a viral infection. Analyses of the phenotypic profile and anatomic distribution of the plasmid IL-12-augmented CTL population indicated that these lymphocytes were primarily effector memory rather than central memory T cells. These observations suggest that CTL-based vaccines should elicit central memory rather than effector memory T cells and illustrate the importance of monitoring the phenotype and functionality of vaccine-induced, antigen-specific CTL.
authors.affiliation: Department of Medicine, Division of Viral Pathogenesis, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Seaman
authors.forename: Fred W
authors.initials: FW
authors.lastname: Peyerl
authors.forename: Shawn S
authors.initials: SS
authors.lastname: Jackson
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Lifton
authors.forename: Darci A
authors.initials: DA
authors.lastname: Gorgone
authors.forename: Jörn E
authors.initials: JE
authors.lastname: Schmitz
authors.forename: Norman L
authors.initials: NL
authors.lastname: Letvin
mesh_terms: D016915:AIDS Vaccines / Q000008:administration & dosage / Q000276:immunology*; D000818:Animals; D003601:Cytotoxicity Tests, Immunologic; D005260:Female; D015699:HIV Envelope Protein gp120 / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology; D006801:Humans; D007117:Immunization, Secondary; D007156:Immunologic Memory; D018664:Interleukin-12 / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D010957:Plasmids; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D014611:Vaccination; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000276:immunology
chemical_list: D016915:AIDS Vaccines; D015699:HIV Envelope Protein gp120; D019444:Vaccines, DNA; D018664:Interleukin-12