Urdahl Kevin B, Sun Joseph C, Bevan Michael J
Department of Immunology and Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA.
Nat Immunol. 2002 Aug;3(8):772-9. doi: 10.1038/ni814. Epub 2002 Jul 1.
Unlike conventional CD8(+) T cells, major histocompatibility complex (MHC) class Ib-restricted CD8(+) T cells show an activated phenotype in uninfected mice and respond rapidly to foreign invaders. The underlying factors that contribute to these differences are not well understood. We show here that the activated phenotype of MHC class Ib-restricted CD8(+) T cells was partially acquired as a result of interactions in the thymus and reflected an increased capacity to be selected via interactions with MHC molecules on hematopoietic cells. Using bone marrow-chimeric mice, we have shown that MHC class Ib-restricted, but not MHC class Ia-restricted, CD8(+) T cells specific for Listeria monocytogenes were efficiently selected when MHC class I was expressed only on hematopoietic cells. Thus, the distinct functional properties of MHC class Ib-restricted versus MHC class Ia-restricted CD8(+) T cells may result, at least in part, from the different ways in which they are positively selected in the thymus.
与传统的CD8(+) T细胞不同，主要组织相容性复合体（MHC）Ib类限制性CD8(+) T细胞在未感染的小鼠中表现出活化表型，并对外来入侵者迅速做出反应。导致这些差异的潜在因素尚未完全了解。我们在此表明，MHC Ib类限制性CD8(+) T细胞的活化表型部分是由于在胸腺中的相互作用而获得的，这反映了通过与造血细胞上的MHC分子相互作用而被选择的能力增强。使用骨髓嵌合小鼠，我们已经表明，当MHC I类仅在造血细胞上表达时，针对单核细胞增生李斯特菌的MHC Ib类限制性而非MHC Ia类限制性CD8(+) T细胞能被有效选择。因此，MHC Ib类限制性与MHC Ia类限制性CD8(+) T细胞不同的功能特性可能至少部分是由于它们在胸腺中被阳性选择的方式不同所致。
