Regulatory CD4 T cells control the size of the peripheral activated/memory CD4 T cell compartment.
The mechanisms leading to stable T cell numbers in the periphery of a healthy animal are, to date, not well understood. We followed the expansion of CD45RBhigh (naive) and CD45RBlow (activated/memory) CD4 T cells transferred from normal mice into syngeneic Rag-20/0 recipients and the dynamics of peripheral reconstitution when both populations were coinjected. Naive cells acquired an activated phenotype and showed a high proliferative capacity that was dependent on the environment in which the recipients were kept (specific pathogen-free vs conventional housing conditions), the age of the recipients, and the presence of CD45RBlow T cells in the injected cohort. CD45RBlow CD4 T cells protected the host from CD45RBhigh CD4 T cell-induced inflammatory bowel disease and showed a limited degree of expansion. CD45RBlow CD4 T cells isolated from GF mice also showed the ability to prevent inflammatory bowel disease, indicating that at least part of the natural regulatory T cells are self-reactive. The results indicate that 1) peripheral T cell expansion in lymphocyte-deficient recipients represent classical immune responses, which are mainly promoted by exogenous Ags and 2) natural regulatory T cells control the size of the activated/memory peripheral CD4 T cell compartment.
Annacker
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O
Unite du Développement des Lymphocytes, Centre National de la Recherche Scientifique, Unité de Recherche Associée 1961, Institut Pasteur, Paris, France. bandeira@pasteur.fr
Burlen-Defranoux
O
O
Pimenta-Araujo
R
R
Cumano
A
A
Bandeira
A
A
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000637:transplantation; D005856:Germ-Free Life / Q000276:immunology; D007156:Immunologic Memory / Q000276:immunology*; D015212:Inflammatory Bowel Diseases / Q000276:immunology; D007399:Interphase / Q000276:immunology; D017493:Leukocyte Common Antigens / Q000096:biosynthesis; D008213:Lymphocyte Activation / Q000276:immunology*; D017710:Lymphocyte Transfusion; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D016513:Mice, SCID; D009928:Organ Specificity / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism
D017493:Leukocyte Common Antigens