Neonates support lymphopenia-induced proliferation.
T cells expand without intentional antigen stimulation when transferred into adult lymphopenic environments. In this study, we show that the physiologic lymphopenic environment existing in neonatal mice also supports CD4 T cell proliferation. Strikingly, naive CD4 T cells that proliferate within neonates acquire the phenotypic and functional characteristics of memory cells. Such proliferation is inhibited by the presence of both memory and naive CD4 T cells, is enhanced by 3-day thymectomy, is independent of IL-7, and requires a class II MHC-TCR interaction and a CD28-mediated signal. CD44(bright) CD4 T cells in neonates have a wide repertoire as judged by the distribution of Vbeta expression. Thus, lymphopenia-induced T cell proliferation is a physiologic process that occurs during the early postnatal period.
Min
Booki
B
Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
McHugh
Rebecca
R
Sempowski
Gregory D
GD
Mackall
Crystal
C
Foucras
Gilles
G
Paul
William E
WE
D000818:Animals; D020296:Animals, Congenic; D000831:Animals, Newborn; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology* / Q000637:transplantation; D002455:Cell Division; D018960:Hyaluronan Receptors / Q000378:metabolism; D007156:Immunologic Memory; D008213:Lymphocyte Activation; D008231:Lymphopenia / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D008285:Major Histocompatibility Complex; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000378:metabolism; D013934:Thymectomy
D018960:Hyaluronan Receptors; D011948:Receptors, Antigen, T-Cell