Identification of fibronectin in chicken thrombocytes

Cell attachment and spreading of chicken embryo fibroblasts and three mammalian cell lines were promoted by using thrombocyte secretion products (TSP) prepared from chicken thrombocytes which are analogous to mammalian platelets. The cell attachment activity following TSP treatment was interfered with by the addition of a synthetic peptide containing the RGD sequence from the cell attachment region of fibronectin (FN). Cell attachment on TSP-coated plates was inhibited by the addition of anti-chicken FN rabbit antiserum, but not by anti-chicken vitronectin (VN) rabbit antiserum. By immunoblotting, immunofluorescent test and sensitive enzyme linked immunosorbent assay using an anti-chicken FN antiserum, the presence of FN in thrombocytes and the release of FN from the cells were demonstrated. The release of FN from thrombocytes was partially induced by the in vitro cultivation of the cells and was further promoted by treatment of the cells with thrombin.