Rapid development of T cell memory.
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.
Wong
Phillip
P
Infectious Diseases Service, Immunology Program, Department of Medicine, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA.
Lara-Tejero
María
M
Ploss
Alexander
A
Leiner
Ingrid
I
Pamer
Eric G
EG
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