M'Rini Christine, Cheng Guiying, Schweitzer Colleen, Cavanagh Lois L, Palframan Roger T, Mempel Thorsten R, Warnock Richard A, Lowe John B, Quackenbush Elizabeth J, von Andrian Ulrich H
CBR Institute for Biomedical Research, Harvard Medical School, Boston, MA 02115, USA.
J Exp Med. 2003 Nov 3;198(9):1301-12. doi: 10.1084/jem.20030182.
Lymphocytes home to peripheral lymph nodes (PLNs) via high endothelial venules (HEVs) in the subcortex and incrementally larger collecting venules in the medulla. HEVs express ligands for L-selectin, which mediates lymphocyte rolling. L-selectin counterreceptors in HEVs are recognized by mAb MECA-79, a surrogate marker for molecularly heterogeneous glycans termed peripheral node addressin. By contrast, we find that medullary venules express L-selectin ligands not recognized by MECA-79. Both L-selectin ligands must be fucosylated by alpha(1,3)-fucosyltransferase (FucT)-IV or FucT-VII as rolling is absent in FucT-IV+VII(-/-) mice. Intravital microscopy experiments revealed that MECA-79-reactive ligands depend primarily on FucT-VII, whereas MECA-79-independent medullary L-selectin ligands are regulated by FucT-IV. Expression levels of both enzymes paralleled these anatomical distinctions. The relative mRNA level of FucT-IV was higher in medullary venules than in HEVs, whereas FucT-VII was most prominent in HEVs and weak in medullary venules. Thus, two distinct L-selectin ligands are segmentally confined to contiguous microvascular domains in PLNs. Although MECA-79-reactive species predominate in HEVs, medullary venules express another ligand that is spatially, antigenically, and biosynthetically unique. Physiologic relevance for this novel activity in medullary microvessels is suggested by the finding that L-selectin-dependent T cell homing to PLNs was partly insensitive to MECA-79 inhibition.
淋巴细胞通过皮质下的高内皮微静脉(HEV)和髓质中逐渐增大的集合微静脉归巢至外周淋巴结(PLN)。HEV表达L-选择素的配体,介导淋巴细胞滚动。HEV中的L-选择素反受体可被单克隆抗体MECA-79识别,MECA-79是一种分子异质性聚糖(称为外周淋巴结地址素)的替代标志物。相比之下,我们发现髓质微静脉表达不被MECA-79识别的L-选择素配体。两种L-选择素配体都必须由α(1,3)-岩藻糖基转移酶(FucT)-IV或FucT-VII进行岩藻糖基化,因为在FucT-IV+VII(-/-)小鼠中不存在滚动现象。活体显微镜实验表明,与MECA-79反应的配体主要依赖于FucT-VII,而与MECA-79无关的髓质L-选择素配体则受FucT-IV调控。这两种酶的表达水平与这些解剖学差异平行。FucT-IV的相对mRNA水平在髓质微静脉中高于HEV,而FucT-VII在HEV中最显著,在髓质微静脉中较弱。因此,两种不同的L-选择素配体被分段限制在PLN中相邻的微血管区域。虽然与MECA-79反应的物质在HEV中占主导,但髓质微静脉表达另一种在空间、抗原性和生物合成上独特的配体。L-选择素依赖性T细胞归巢至PLN对MECA-79抑制部分不敏感这一发现提示了这种在髓质微血管中的新活性的生理相关性。