Chambers W H, Oeltmann T N
Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN.
Lymphokine Res. 1990 Summer;9(2):239-45.
Alpha-mannosidase was tested for its ability to inhibit lytic activity of nonadherent, mononuclear peripheral blood leukocytes (PBL) against K-562 target cells. Pretreatment of effector cells (60 min., 37 degrees C, pH 7.3) with this enzyme, prior to and after exhaustive dialysis, was examined. Nondialyzed enzyme preparations completely inhibited NK lytic function at all concentrations tested (1.0, 0.5, and 0.25 units/ml). On the other hand, dialyzed enzyme preparations had no inhibitory effect on NK lytic function over the same range of concentrations. The inhibitory effects of the nondialyzed enzyme were due to the presence of (NH4)2SO4, which could be removed by dialysis. Studies were also performed to determine whether enzyme treatment of effector cells resulted in hexose release from cell surface structures. Treatment of effector cells with alpha-mannosidase (dialyzed preparation) resulted in a dose dependent release of mannose. These data demonstrate that NK cell lytic function is not inhibited by pretreatment of effector cells with alpha-mannosidase even though mannose is quantitatively released from cell surface oligosaccharide structures. These results suggest that NK lytic function does not involve an effector cell surface structure bearing terminal alpha-linked mannose residues as previously reported.
对α-甘露糖苷酶抑制非贴壁单核外周血白细胞（PBL）对K-562靶细胞的裂解活性的能力进行了测试。在彻底透析前后，对效应细胞（60分钟，37摄氏度，pH 7.3）用该酶进行预处理进行了检查。未透析的酶制剂在所有测试浓度（1.0、0.5和0.25单位/毫升）下均完全抑制NK裂解功能。另一方面，透析后的酶制剂在相同浓度范围内对NK裂解功能没有抑制作用。未透析酶的抑制作用归因于（NH4）2SO4的存在，其可通过透析去除。还进行了研究以确定效应细胞的酶处理是否导致己糖从细胞表面结构释放。用α-甘露糖苷酶（透析制剂）处理效应细胞导致甘露糖呈剂量依赖性释放。这些数据表明，即使甘露糖从细胞表面寡糖结构中定量释放，效应细胞用α-甘露糖苷酶预处理也不会抑制NK细胞裂解功能。这些结果表明，NK裂解功能不涉及如先前报道的带有末端α-连接甘露糖残基的效应细胞表面结构。
