Virtanen I, Ylänne J, Vartio T, Saksela E
Department of Anatomy, University of Helsinki, Finland.
Scand J Immunol. 1991 Apr;33(4):421-8. doi: 10.1111/j.1365-3083.1991.tb01790.x.
Human natural killer (NK) cells adhered and most of them also actively spread on cellular fibronectin (cFn), plasma Fn (pFn) and its Mr 120,000-140,000 or Mr 105,000 cell-binding proteolytic Fn-fragments as well as on heparin-binding Fn-fragments containing the alternative cell binding site. The cells did not spread on vitronectin, laminin or collagens. Adhesion on Mr 105,000 Fn fragment containing the cell binding site, could be prevented by the synthetic peptide GRGDS but not by an inactive peptide, whereas adhesion on heparin-binding Fn fragments was unaffected by the peptide. Spreading of the NK cells led to a distinct reorganization of F-actin. Immunoprecipitation with monoclonal antibodies (MoAb) against the beta 1 integrin subunit of radioactively surface-labelled cells revealed a broad polypeptide band of Mr 140,000 under reducing conditions and a polypeptide doublet of Mr 160,000 and Mr 110,000 under non-reducing conditions. Identical polypeptides, corresponding to the alpha- and beta-subunits of the Fn-receptor complex, were bound to the Mr 105,000 chymotryptic Fn-fragment coupled to Sepharose. Similar experiments with small lymphocytes did not reveal any polypeptides. Immunofluorescence results with McAbs suggested that among the alpha-subunits of integrins, the alpha 3, alpha 4, and alpha 5 subunits are expressed in NK cells. The present results suggest that non-activated NK cells, but not small lymphocytes, express beta 1-integrins, and that at least the Fn-receptors alpha 4 beta 1 and alpha 5 beta 1 may function in the adhesion and migration of NK cells.
人类自然杀伤（NK）细胞能黏附于细胞纤连蛋白（cFn）、血浆纤连蛋白（pFn）及其分子量为120,000 - 140,000或105,000的细胞结合性蛋白水解纤连蛋白片段以及含有替代性细胞结合位点的肝素结合纤连蛋白片段上，并且大多数细胞还能在这些片段上积极铺展。细胞不会在玻连蛋白、层粘连蛋白或胶原上铺展。在含有细胞结合位点的分子量为105,000的纤连蛋白片段上的黏附可被合成肽GRGDS阻止，但不能被无活性肽阻止，而在肝素结合纤连蛋白片段上的黏附不受该肽影响。NK细胞的铺展导致F - 肌动蛋白明显重排。用针对放射性表面标记细胞的β1整合素亚基的单克隆抗体（MoAb）进行免疫沉淀，在还原条件下显示出一条分子量为140,000的宽多肽带，在非还原条件下显示出分子量为160,000和110,000的多肽双峰。与结合到琼脂糖上的分子量为105,000的胰凝乳蛋白酶纤连蛋白片段结合的是与纤连蛋白受体复合物的α和β亚基相对应的相同多肽。对小淋巴细胞进行的类似实验未显示出任何多肽。用单克隆抗体进行的免疫荧光结果表明，在整合素的α亚基中，α3、α4和α5亚基在NK细胞中表达。目前的结果表明，未活化的NK细胞而非小淋巴细胞表达β1整合素，并且至少纤连蛋白受体α4β1和α5β1可能在NK细胞的黏附和迁移中起作用。
