Reactivity of naive CD4+CD25- T cells against gut microflora in healthy mice.
We have previously shown that conventional as well as germ-free CD4+ T cells depleted of CD25+ cells from the gut-associated lymphoid tissue and the periphery proliferate specifically in response to enterobacterial antigen exposure whereas unfractionated CD4+ T cells are not reactive under these conditions. Here we show that the majority of the enteroantigen-specific CD4+ CD25- T cells are naive cells expressing a CD45RB high, CD62L high and CD44 low phenotype. These cells are also present in the thymus and data from adult thymectomized mice show that they represent late (>6 weeks) thymic emigrants. Upon enteroantigen activation, the CD4+ CD25- T cells secrete IL-4, IL-5, IL-10, granulocyte macrophage colony-stimulating factor, tumor necrosis factor-alpha and IFN-gamma. Clonotype mapping of the TCRBV regions 1-18 of enteroantigen-reactive CD4+ CD25- T cells by TCR clonotype mapping revealed the polyclonal nature of this subset. In conclusion, we have for the first time demonstrated the presence of an evolutionary, functionally conserved subset of CD4+ T cells, which are reactive against enterobacterial antigens. This subset resides both in the thymus and the periphery; it is not dependent on previous antigen experience and represents late thymic emigrants, which by enteroantigen-induced activation express a mixed Th 1-Th 2 phenotype. At homeostatic conditions, CD25+ T cells maintain peripheral tolerance in this CD4+ T cell subset.
Gad
Monika
M
Department of Medical Anatomy, Panum Institute, University of Copenhagen, Building 18.3, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark. m.gad@mai.ku.dk
Lundsgaard
Dorthe
D
Kjellev
Stine
S
Kristensen
Nanna N
NN
Seremet
Tina
T
Straten
Per Thor
PT
Claesson
Mogens H
MH
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D016827:CD8 Antigens / Q000276:immunology; D016207:Cytokines / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D007422:Intestines / Q000276:immunology* / Q000382:microbiology*; D008221:Lymphoid Tissue / Q000166:cytology / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D016513:Mice, SCID; D015375:Receptors, Interleukin-2 / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology / Q000378:metabolism; D018418:Th2 Cells / Q000276:immunology / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology
D016827:CD8 Antigens; D016207:Cytokines; D015375:Receptors, Interleukin-2