Effector T cell differentiation and memory T cell maintenance outside secondary lymphoid organs.
Naive T cell circulation is restricted to secondary lymphoid organs. Effector and memory T cells, in contrast, acquire the ability to migrate to nonlymphoid tissues. In this study we examined whether nonlymphoid tissues contribute to the differentiation of effector T cells to memory cells and the long-term maintenance of memory T cells. We found that CD4, but not CD8, effector T cell differentiation to memory cells is impaired in adoptive hosts that lack secondary lymphoid organs. In contrast, established CD4 and CD8 memory T cells underwent basal homeostatic proliferation in the liver, lungs, and bone marrow, were maintained long-term, and functioned in the absence of secondary lymphoid organs. CD8 memory T cells found in nonlymphoid tissues expressed both central and effector memory phenotypes, whereas CD4 memory T cells displayed predominantly an effector memory phenotype. These findings indicate that secondary lymphoid organs are not necessary for the maintenance and function of memory T cell populations, whereas the optimal differentiation of CD4 effectors to memory T cells is dependent on these organs. The ability of memory T cells to persist and respond to foreign Ag independently of secondary lymphoid tissues supports the existence of nonlymphoid memory T cell pools that provide essential immune surveillance in the periphery.
Obhrai
Jagdeep S
JS
Section of Nephrology, Department of Internal Medicine, and Section of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA.
Oberbarnscheidt
Martin H
MH
Hand
Timothy W
TW
Diggs
Lonnette
L
Chalasani
Geetha
G
Lakkis
Fadi G
FG
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D006706:Homeostasis; D007156:Immunologic Memory / Q000276:immunology*; D008221:Lymphoid Tissue / Q000166:cytology* / Q000276:immunology*; D051379:Mice; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology*