Sialyl Lewis X binding lectins on natural killer cells and their functions

自然杀伤（NK）细胞通过细胞表面受体（包括凝集素样受体）介导细胞毒性。我们研究了唾液酸化刘易斯X（sLeX）抗原Neu 5Ac α2，3Galβ 1，4（Fucα 1，3）GlcNAc-R是否可以与人NK衍生的KHYG细胞上的凝集素样受体结合，使用人肝癌衍生的HepG 2细胞（Hep-TF）分泌的转铁蛋白，HepG 2细胞的N-聚糖富含α 1，3-岩藻糖基化双-、三-和四-触角复合型N-聚糖，从岩藻糖基转移酶3转染的细胞中分离的高表达sLeX的红白血病衍生的K562细胞对KHYG细胞的敏感性是野生型K562细胞的2.5倍。异硫氰酸黄绿素（FITC）标记的Hep-TF与KHYG细胞的结合强度是FITC标记的Nor-TF的1.8倍。通过抗NKG 2D、抗NKG 2C、抗CD 94和抗CD 161抗体处理抑制结合。与野生型U937细胞相比，FITC标记的Hep-TF与NKG 2D和CD 94转染的人单核细胞衍生的U937细胞的结合更强。此外，KHYG细胞中17 kDa蛋白的酪氨酸磷酸化通过在Hep-TF包被的板上孵育和用抗NKG 2D抗体处理而增强，但不通过Nor-TF包被的板和抗CD 94抗体。这些结果表明，sLeX抗原与NK细胞上的凝集素样受体的相互作用诱导细胞毒性，这是通过酪氨酸磷酸化的17 kDa蛋白介导的。

Natural killer (NK) cells mediate cytotoxicity through cell-surface receptors including lectin-like receptors. We have investigated whether sialyl Lewis X (sLeX) antigen, Neu5Acα2,3Galβ1,4 (Fucα1,3)GlcNAc-R, can bind to the lectin-like receptor on human NK-derived KHYG cells, using transferrin secreted by human hepatoma-derived HepG2 cells (Hep-TF), whose N-glycans are rich in α1,3-fucosylated bi-, tri-, and tetra-antennary complex types of N-glycans, and commercially available human transferrin (Nor-TF), which is comprised of bi-antennary N-glycans without α1,3-fucosylation.High sLeX-expressing erythroleukemia-derived K562 cells isolated from fucosyltransferase 3-transfected cells were 2.5 fold more susceptible than wild-type K562 cells to KHYG cells. Fluorescein isothiocyanate (FITC)-labeled Hep-TF bound 1.8 fold more strongly to KHYG cells than did FITC-labeled Nor-TF. The binding was suppressed by treatment with anti-NKG2D, anti-NKG2C, anti-CD94, and anti-CD 161 antibodies. FITC-labeled Hep-TF bound more strongly to human monocyte-derived U937 cells transfected with NKG2D and CD94 than to wild-type U937 cells. Moreover, tyrosine phosphorylation of a 17 kDa protein in the KHYG cells was enhanced by incubation on a Hep-TF coated plate and treatment with an anti-NKG2D antibody, but not by a Nor-TF coated plate and an anti-CD94 antibody.These results indicated that the interaction of sLeX antigen with the lectin-like receptors on NK cells induces cytotoxicity, which is mediated through a tyrosine-phosphorylated 17 kDa protein.