title: Characterization of antigens recognized by natural killer cells in cell-culture supernatants.
abstract: Inhibitors of natural killer (NK) cell activity in cell-culture supernatants, believed to be antigens recognized by NK cells, were defined by their ability to inhibit NK cells in 51Cr-release cytotoxic assays. Supernatants from cultures of melanoma cells and Chang cells were used as the source of the antigen. Partial characterization by a number of sequential separation procedures suggested that the antigens were glycoproteins in the size range 120-140,000 daltons which had affinity for both concanavalin A and wheat germ lectin. Inhibitory activity was destroyed by trypsin digestion, but was resistant to neuraminidase and a number of physical procedures. Addition of supernatants to NK assays against a number of different target cells indicated that inhibition was restricted to certain target cells. This indicated that the inhibition of NK cells was not non-specific, and that the antigens were not expressed on all target cells. These studies provide a basis for further analysis of antigens recognized by NK cells, and allow investigation of their role in vivo in tumour-bearing hosts.
mesh_terms: D000818:Animals; D000920:Antibody-Dependent Cell Cytotoxicity; D000951:Antigens, Neoplasm / Q000302:isolation & purification; D002460:Cell Line; D002478:Cells, Cultured; D002846:Chromatography, Affinity; D003601:Cytotoxicity Tests, Immunologic; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology*; D051379:Mice
chemical_list: D000951:Antigens, Neoplasm