title: Rapid development of T cell memory.
abstract: Prime-boost immunization is a promising strategy for inducing and amplifying pathogen- or tumor-specific memory CD8 T cell responses. Although expansion of CD8 T cell populations following the second Ag dose is integral to the prime-boost strategy, it remains unclear when, after priming, memory T cells become competent to proliferate. In this study, we show that Ag-specific CD8 T cells with the capacity to undergo extensive expansion are already present at the peak of the primary immune response in mice. These early memory T cells represent a small fraction of the primary immune response and, at early time points, their potential to proliferate is obscured by large effector T cell populations that rapidly clear Ag upon reimmunization. With sufficient Ag boosting, however, secondary expansion of these memory cells can be induced as early as 5-7 days following primary immunization. Importantly, both early and delayed boosting result in similar levels of protective immunity to subsequent pathogen challenge. Early commitment and differentiation of memory T cells during primary immunization suggest that a short duration between priming and boosting is feasible, providing potential logistic advantages for large-scale prime-boost vaccination of human populations.
authors.affiliation: Infectious Diseases Service, Immunology Program, Department of Medicine, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA.
authors.forename: Phillip
authors.initials: P
authors.lastname: Wong
authors.forename: María
authors.initials: M
authors.lastname: Lara-Tejero
authors.forename: Alexander
authors.initials: A
authors.lastname: Ploss
authors.forename: Ingrid
authors.initials: I
authors.lastname: Leiner
authors.forename: Eric G
authors.initials: EG
authors.lastname: Pamer
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002454:Cell Differentiation / Q000276:immunology; D002455:Cell Division / Q000276:immunology; D007114:Immunization; D007117:Immunization, Secondary; D007156:Immunologic Memory; D007700:Kinetics; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C