Showing papers by "Michael D. Pierschbacher published in 1983"

Serum spreading factor (vitronectin) is present at the cell surface and in tissues

Abstract: Monoclonal antibodies were prepared against a cell attachment-promoting protein, serum spreading factor, which had been partially purified from human serum by chromatography on glass bead columns. The antibodies selected were those that reacted with polypeptides that had cell attachment-promoting activity after sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Immunochromatography of human plasma on columns containing the monoclonal antibodies followed by affinity chromatography on heparin-Sepharose yielded material that in sodium dodecyl sulfate/polyacrylamide gel electrophoretic analysis gave polypeptides of molecular mass 65 and 75 kilodaltons. Both polypeptides bound each of three monoclonal antibodies and had cell attachment-promoting activity after transfer to nitrocellulose filters. Immunofluorescent staining of tissues with the monoclonal antibodies revealed a fibrillar pattern that was mostly associated with loose connective tissue and overlapped with fibronectin fibrils. Fetal membrane tissue, which showed strong staining with the antibodies in immunofluorescence, also gave 65- and 75-kilodalton polypeptides with cell attachment-promoting activity after chromatography on columns containing the monoclonal antibodies. One source of the tissue protein may be fibroblastic cells, because cultured human fibroblasts also stained with the monoclonal antibodies. The staining was fibrillar and appeared to be associated with the cell surface extracellular matrix. We propose the name "vitronectin" for the various forms of this protein, on the basis of its binding to glass and its adhesive properties.

Synthetic peptide with cell attachment activity of fibronectin

Abstract: Four synthetic peptides that together constitute the cell attachment domain of fibronectin [Pierschbacher, M.D., Ruoslahti, E., Sundelin, J., Lind, P. & Peterson, P. (1982) J. Biol. Chem. 257, 9593-9597] were constructed and tested for their ability to induce cell attachment and spreading. One of these peptides, consisting of the 30 amino acid residues nearest the COOH terminus of the domain, contained all of the cell attachment activity of the whole domain. Under suitable conditions the peptide was approximately as active as intact fibronectin on a molar basis. The activity could be demonstrated by binding the peptide to polystyrene directly, or via albumin, or by coupling it to agarose beads. This synthetic peptide will be useful in the elucidation of the molecular details of the attachment of cells to fibronectin and could allow manipulation of the adhesive properties of cell culture surfaces and prosthetic materials.

Induction of T-cell maturation by a cloned line of thymic epithelium (TEPI)

Abstract: A cloned cell line of thymic origin has been characterized as epithelial in nature. A description of the procedures for derivation and cloning of the cell line includes use of epidermal growth factor. The thymic epithelial (TEPI) cell line is Ia antigen positive, forms desmosomes, and produces an extracellular fibronectin matrix. The supernatant from confluent monolayers of TEPI was tested for its ability to promote thymocyte functional activity. TEPI supernatant (TEPI SN) was demonstrated to greatly enhance the response of peanut agglutinin-positive thymocytes to alloantigen, as measured by cell-mediated lympholysis. Furthermore, preincubation of peanut agglutinin-positive thymocytes with TEPI SN prior to allostimulation resulted in marked enhancement, thus distinguishing it from interleukin 2. Finally, TEPI SN was demonstrated to induce interleukin 2 production by peanut agglutinin-positive thymocytes in the presence of concanavalin A. This activity was demonstrated not to be due to interleukin 1, which is absent in TEPI SN. Preliminary biochemical analysis indicates that the biological activity is associated with a Mr 50,000 entity. The data suggest that TEPI produces a soluble factor capable of inducing function of an immature thymocyte subpopulation into an IL 2 producer.