Distinct CD4+ helper T cells involved in primary and secondary responses to infection.
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.
Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO 63110, USA.
K Scott
KS
Weber
Qi-Jing
QJ
Li
Stephen P
SP
Persaud
Jeff D
JD
Campbell
Mark M
MM
Davis
Paul M
PM
Allen
D000595:Amino Acid Sequence; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000382:microbiology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D049109:Cell Proliferation; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D008089:Listeria monocytogenes / Q000276:immunology; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid
D000939:Epitopes