Homma T, Hosono O, Iwata S, Ando S, Sasaki K, Nishi T, Kawasaki H, Tanaka H, Morimoto C
University of Tokyo, Japan.
Arthritis Rheum. 2001 Feb;44(2):296-306. doi: 10.1002/1529-0131(200102)44:2<296::AID-ANR46>3.0.CO;2-Z.
We have previously reported that the anti-6C2 monoclonal antibody (mAb) defines a subset of human CD4+ memory T cells. The present study sought to determine the nature of the 6C2 molecule and the function associated with 6C2+ T cells, and to examine whether this T cell subset is involved in the pathophysiology of rheumatoid arthritis (RA).
Cytofluorographic analysis was performed for identification of T cell surface molecules displaying a distribution similar to that of the 6C2 molecule. T cells in the synovial fluid of RA patients were examined for expression of the 6C2 molecule. Transendothelial migratory activity was assessed by assay using monolayers of human endothelial cells. Specific reactivity of the anti-6C2 mAb was determined by immunoblotting on gangliosides separated by thin-layer chromatography, and flow cytometric analysis of the cells transfected with complementary DNA (cDNA) was performed for determination of the glycosyltransferases involved in biosynthesis of the gangliosides.
On human peripheral T cells, the 6C2 molecule was distributed, by and large, in a pattern similar to that of CDw60, or O-acetyl-GD3. The majority (>70%) of synovial fluid T cells from patients with RA were found to be 6C2 positive, and those 6C2+ T cells exhibited a transendothelial migratory capacity that was inhibited by pretreatment of T cells with anti-6C2 mAb. Moreover, treatment of T cells with neuraminidase resulted in a loss of 6C2 expression as well as a reduction in the transendothelial migratory activity. Anti-6C2 mAb reacted specifically with GD3, but not with O-acetyl-GD3. The reactivity of anti-6C2 mAb was induced on the cell surface only by transfection with cDNA for GD3 synthase.
The 6C2 molecule is a disialoganglioside, GD3, and is present on a subset of T cells with transendothelial migratory capacity. The 6C2/GD3 molecules, as well as 6C2/GD3+ T cells, appear to play a role in T cell migration and in the inflammation of RA.
我们之前报道过抗6C2单克隆抗体（mAb）可定义人类CD4+记忆性T细胞的一个亚群。本研究旨在确定6C2分子的性质以及与6C2+ T细胞相关的功能，并研究该T细胞亚群是否参与类风湿关节炎（RA）的病理生理过程。
进行细胞荧光分析以鉴定显示出与6C2分子相似分布的T细胞表面分子。检测RA患者滑液中的T细胞是否表达6C2分子。通过使用人内皮细胞单层进行检测来评估跨内皮迁移活性。通过对经薄层层析分离的神经节苷脂进行免疫印迹来确定抗6C2 mAb的特异性反应性，并对转染了互补DNA（cDNA）的细胞进行流式细胞术分析，以确定参与神经节苷脂生物合成的糖基转移酶。
在人外周T细胞上，6C2分子的分布总体上与CDw60或O-乙酰-GD3相似。发现大多数（>70%）RA患者的滑液T细胞为6C2阳性，并且那些6C2+ T细胞表现出跨内皮迁移能力，用抗6C2 mAb预处理T细胞可抑制这种能力。此外，用神经氨酸酶处理T细胞会导致6C2表达丧失以及跨内皮迁移活性降低。抗6C2 mAb与GD3特异性反应，但不与O-乙酰-GD3反应。抗6C2 mAb的反应性仅通过用GD3合酶的cDNA转染才在细胞表面诱导产生。
6C2分子是一种二唾液酸神经节苷脂，即GD3，存在于具有跨内皮迁移能力的T细胞亚群上。6C2/GD3分子以及6C2/GD3+ T细胞似乎在T细胞迁移和RA炎症中起作用。
