Mohan Karkada, Pinto Devanand, Issekutz Thomas B
Departments of. Pediatrics, Microbiology/Immunology and Pathology, Dalhousie University, and Institute for Marine Biosciences, National Research Council, Halifax, Nova Scotia, Canada.
J Immunol. 2003 Sep 15;171(6):3179-86. doi: 10.4049/jimmunol.171.6.3179.
During inflammation, T lymphocytes migrate out of the blood across the vascular endothelium in a multistep process. The receptors mediating T cell adhesion to endothelium are well characterized; however, the molecules involved in T cell transendothelial migration (TEM) subsequent to lymphocyte adhesion to the endothelium are less clear. To identify receptors mediating TEM, mAbs were produced against human blood T cells adhering to IFN-gamma-activated HUVEC in mice and tested for inhibition of lymphocyte TEM across cytokine-activated HUVEC. Most of the mAbs were against beta(1) and beta(2) integrins, but one mAb, 6B9, significantly inhibited T cell TEM across IFN-gamma, TNF-alpha, and IFN-gamma plus TNF-alpha-stimulated HUVEC, and did not react with an integrin. 6B9 mAb did not inhibit T cell adhesion to HUVEC, suggesting that 6B9 blocked a novel pathway in T cell TEM. The 6B9 Ag was 80 kDa on SDS-PAGE, and was expressed by both blood leukocytes and HUVEC. Immunoaffinity purification and mass spectrometry identified this Ag as tissue transglutaminase (tTG), a molecule not known to mediate T cell TEM. Treatment of HUVEC with 6B9 was more effective than treatment of T cells. 6B9 blockade selectively inhibited CD4(-), but not CD4(+), T cell TEM, suggesting a role for tTG in recruitment of CD8(+) T lymphocytes. Thus, 6B9 is a new blocking mAb to human tTG, which demonstrates that tTG may have a novel role in mediating CD8(+) T cell migration across cytokine-activated endothelium and infiltration of tissues during inflammation.
在炎症过程中，T淋巴细胞以多步骤方式从血液中穿过血管内皮迁移出来。介导T细胞与内皮细胞黏附的受体已得到充分表征；然而，淋巴细胞黏附于内皮细胞后参与T细胞跨内皮迁移（TEM）的分子尚不清楚。为了鉴定介导TEM的受体，制备了针对在小鼠中黏附于干扰素-γ激活的人脐静脉内皮细胞（HUVEC）的人血T细胞的单克隆抗体（mAb），并测试其对细胞因子激活的HUVEC上淋巴细胞TEM的抑制作用。大多数mAb针对β(1)和β(2)整合素，但一种mAb，即6B9，显著抑制T细胞通过干扰素-γ、肿瘤坏死因子-α以及干扰素-γ加肿瘤坏死因子-α刺激的HUVEC的TEM，且不与整合素发生反应。6B9 mAb不抑制T细胞与HUVEC的黏附，这表明6B9阻断了T细胞TEM中的一条新途径。6B9抗原在SDS-PAGE上为80 kDa，在血液白细胞和HUVEC中均有表达。免疫亲和纯化和质谱分析确定该抗原为组织转谷氨酰胺酶（tTG），一种未知介导T细胞TEM的分子。用6B9处理HUVEC比处理T细胞更有效。6B9阻断选择性抑制CD4(-)，而非CD4(+)，T细胞TEM，提示tTG在CD8(+) T淋巴细胞募集中的作用。因此，6B9是一种针对人tTG的新型阻断mAb，表明tTG可能在介导CD8(+) T细胞穿过细胞因子激活的内皮细胞迁移以及炎症期间组织浸润中具有新作用。
