Abstract
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.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.