Katoh Y, Ono S, Takahama Y, Miyake K, Hamaoka T
J Immunol. 1986 Nov 1;137(9):2871-7.
We investigated the role of carbohydrates in the interaction of a B cell differentiation factor designated as B151-TRF2 derived from B151K12 T cell hybridoma with the corresponding receptor on B cells. Induction of polyclonal differentiation of unprimed B cells into IgM-secreting cells by B151-TRF2 was specifically inhibited by addition of N-acetyl-D-glucosamine (GlcNAc) but not by structurally unrelated monosaccharides such as D-galactose, D-glucose, and N-acetyl-D-galactosamine (GalNAc). Absorption of B151-TRF2 activity with spleen cells was specifically inhibited by the presence of GlcNAc. These results indicate that GlcNAc residues are involved in the interaction of B151-TRF2 with the receptor on B cells. To gain insight into mechanism by which GlcNAc inhibits B151-TRF2-mediated B cell responses, the existence of GlcNAc residues was examined on the B151-TRF2 molecule and the corresponding receptor on the B cell surface. The results revealed that B151-TRF2 molecule was not bound to various lectin-coupled agarose beads so far tested, suggesting absence of carbohydrate moieties on the B151-TRF2 molecule. By contrast, pretreatment of spleen cells with trypsin or glycosidase mixture abolished their ability to absorb B151-TRF2 activity. Moreover, B151-TRF2-absorbing ability of spleen cells disappeared by the pretreatment with beta-N-acetylglucosaminidase, which cleaves terminal GlcNAc. The fact that pnitrophenyl (PNP)-GlcNAc specifically inhibited such enzyme activity on target cells indicates that terminal GlcNAc on the B cell surface plays a crucial role in the interaction with B151-TRF2 molecule. Interestingly, it was also found that B151-TRF2 activity was trapped and eluted from GlcNAc-coupled agarose beads. Taken collectively, these results strongly suggest that B cell membrane receptors for B151-TRF2 comprise glycoproteins with a terminal GlcNAc residue(s), and that binding of B151-TRF2 with terminal GlcNAc on the receptor is important for the subsequent activation of B cells.
我们研究了碳水化合物在一种名为B151 - TRF2的B细胞分化因子（源自B151K12 T细胞杂交瘤）与B细胞上相应受体相互作用中的作用。B151 - TRF2诱导未致敏B细胞多克隆分化为分泌IgM的细胞，这种诱导作用可被添加N - 乙酰 - D - 葡萄糖胺（GlcNAc）特异性抑制，但不能被结构不相关的单糖如D - 半乳糖、D - 葡萄糖和N - 乙酰 - D - 半乳糖胺（GalNAc）抑制。GlcNAc的存在可特异性抑制脾细胞对B151 - TRF2活性的吸收。这些结果表明，GlcNAc残基参与了B151 - TRF2与B细胞上受体的相互作用。为深入了解GlcNAc抑制B151 - TRF2介导的B细胞反应的机制，我们检测了B151 - TRF2分子和B细胞表面相应受体上GlcNAc残基的存在情况。结果显示，B151 - TRF2分子不与目前所测试的各种凝集素偶联琼脂糖珠结合，这表明B151 - TRF2分子上不存在碳水化合物部分。相比之下，用胰蛋白酶或糖苷酶混合物预处理脾细胞会消除它们吸收B151 - TRF2活性的能力。此外，用β - N - 乙酰氨基葡萄糖苷酶预处理脾细胞后，其吸收B151 - TRF2的能力消失，该酶可切割末端GlcNAc。对硝基苯基（PNP）- GlcNAc特异性抑制靶细胞上这种酶活性这一事实表明，B细胞表面的末端GlcNAc在与B151 - TRF2分子的相互作用中起关键作用。有趣的是，还发现B151 - TRF2活性可被GlcNAc偶联琼脂糖珠捕获并洗脱。综合来看，这些结果强烈表明，B151 - TRF2的B细胞膜受体由带有末端GlcNAc残基的糖蛋白组成，并且B151 - TRF2与受体上末端GlcNAc的结合对于随后B细胞的激活很重要。
