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：2012
卷号：109
期号：24
页码：9511-9516
DOI：10.1073/pnas.1202408109
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Helper T cells are critical for protective immunity, CD8+ T-cell memory, and CD4+ recall responses, but whether the same or distinct CD4+ T cells are involved in these responses has not been established. Here we describe two CD4+ T cells, LLO118 and LLO56, specific for an immunodominant Listeria monocytogenes epitope, with dramatically different responses to primary and secondary infection. Comparing in vivo responses, LLO118 T cells proliferate more strongly to primary infection, whereas surprisingly, LLO56 has a superior CD4+ recall response to secondary infection. LLO118 T cells provide more robust help for CD8+ T-cell responses to secondary infection than LLO56. We found no detectable differences in antigen sensitivity, but naive LLO118 T cells have much lower levels of CD5 and their T-cell receptor levels are dramatically down-regulated after their strong primary response. Thus, distinct CD4+ helper T cells are specialized to help either in primary or secondary responses to infection.
