期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1996
卷号：93
期号：18
页码：9716-9723
DOI：10.1073/pnas.93.18.9716
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：This study evaluated whether T-cell memory reflects increased precursor frequencies of specific long-lived T cells and/or a low-level immune response against some form of persistent antigen. Antivirally protective CD8+ T-cell memory was analyzed mostly in the original vaccinated host to assess the role of antigen in its maintenance. T-cell mediated resistance against reinfection was measured in the spleen and in peripheral solid organs with protocols that excluded protection by antibodies. In vivo protection was compared with detectable cytotoxic T-lymphocyte precursor frequencies determined in vitro. In the spleen, in vitro detectable cytotoxic T-lymphocyte precursor frequencies remained stable independently of antigen, conferring resistance against viral replication in the spleen during reinfection. In contrast, T-cell mediated resistance against reinfection of peripheral solid organs faded away in an antigen-dependent fashion within a few days or weeks. We show that only memory T cells persistently or freshly activated with antigen efficiently extravasate into peripheral organs, where cytotoxic T lymphocytes must be able to exert effector function immediately; both the capacity to extravasate and to rapidly exert effector function critically depend on restimulation by antigen. Our experiments document that the duration of T-cell memory protective against peripheral reinfection depended on the antigen dose used for immunization, was prolonged when additional antigen was provided, and was abrogated after removal of antigen. We conclude that T-cell mediated protective immunity against the usual peripheral routes of reinfection is antigen-dependent.
