First Author | Jay DC | Year | 2008 |
Journal | J Immunol | Volume | 180 |
Issue | 5 | Pages | 2805-14 |
PubMed ID | 18292501 | Mgi Jnum | J:131725 |
Mgi Id | MGI:3774247 | Doi | 10.4049/jimmunol.180.5.2805 |
Citation | Jay DC, et al. (2008) Polyclonal MHC Ib-Restricted CD8+ T Cells Undergo Homeostatic Expansion in the Absence of Conventional MHC-Restricted T Cells. J Immunol 180(5):2805-14 |
abstractText | Naive T cells have the capacity to expand in a lymphopenic environment in a process called homeostatic expansion, where they gain a memory-like phenotype. Homeostatic expansion is dependent on competition for a number of factors, including growth factors and interactions with their selecting self-MHC molecules. In contrast to conventional T cells, it is unclear whether class Ib-restricted CD8(+) T cells have a capacity to undergo homeostatic expansion. In this study, we demonstrate that polyclonal MHC Ib-restricted CD8(+) T cells can undergo homeostatic expansion and that their peripheral expansion is suppressed by conventional MHC-restricted T cells. The acute depletion of CD4(+) T cells in MHC class Ia-deficient K(b-/-)D(b-/-) mice led to the substantial expansion of class Ib-restricted CD8(+) T cells. Adoptive transfer of class Ib-restricted CD8(+) T cells to congenic lymphopenic recipients revealed their ability to undergo homeostatic expansion in a MHC Ib-dependent manner. To further study the homeostatic expansion of MHC Ib-restricted T cells in the absence of all conventional MHC-restricted T cells, we generated mice that express only MHC Ib molecules by crossing H-2K(b-/-)D(b-/-) with CIITA(-/-) mice. CD8(+) T cells in these mice exhibit all of the hallmarks of naive T cells actively undergoing homeostatic expansion with constitutive memory-like surface and functional phenotype. These findings provide direct evidence that MHC Ib-restricted CD8(+) T cells have the capacity to undergo homeostatic expansion. Their peripheral expansion is suppressed under normal conditions by a numerical excess of conventional MHC class Ia- and class II-restricted T cells. |