Invasive behavior of mouse sarcoma cells is inhibited by blocking a 37,000-dalton plasma membrane glycoprotein with Fab fragments.

Abercrombie 's confronted explant technique was used to study the role of tumor surface antigens in malignant invasion. Plasma membranes were isolated from mouse sarcoma cells ( FS9 ) and a mouse cell line (L929) of the same H-2 haplotype. FS9 cells are highly invasive when confronted with chicken heart fibroblasts, whereas the L929 cells are not [ Abercrombie , M. (1979) Nature (London) 281, 259-262]. The FS9 plasma membranes contained significantly higher concentrations of a 37,000-dalton glycoprotein. When antiserum directed against FS9 plasma membranes was preabsorbed with L929 cells, the antibodies remaining reacted predominantly with the 37,000-dalton antigen. Fab fragment prepared from the preabsorbed antiserum inhibited the invasion of chicken heart fibroblasts by FS9 cells. Fab prepared from a monoclonal antibody directed against the 37,000-dalton antigen also inhibited invasivity , whereas monoclonal antibodies reacting with two other FS9 cell surface antigens did not. The results imply a relationship between the increased concentration of the 37,000-dalton glycoprotein on the surface of the FS9 cells and their invasivity .