Reagents Specific for Cell Surface Components

Abstract

Hg, diazonium ions and dyes which bind nucleic acids were covalently linked to dextrans using methods that resulted in non-hydrolyzable reagent-dextran bond without impairing the binding abilities of the reagents, i.e., these dextran derivatives reacted with thiols, phenols/imidazoles and nucleic acids, respectively. Since these dextran derivatives cannot penetrate into cells and since dextran itself does not bind to cells [Friend Murine erythroleukemic cells], these compounds represent reagents specific for the cell surface. They may be used to evaluate cell surface constituents of intact cells and to affect viable cells via an interaction with those constituents. Hg-dextran bound to cells; the amount of Hg thus attached to the cells was about 10 times smaller than when an equivalent concentration of free Hg ions was used. Hg-dextran, bound to cells after a 30 min exposure at room temperature, was localized on the surface of these cells, as sodium borohydride reduced this complex giving rise to the intact cells, elementary Hg and free dextran which was released into medium. When cells were constantly exposed to the Hg-dextran, its toxic effects were comparable to that of free Hg ions. Diazonium-dextran, which also binds tightly to the cell surface, was also considerably toxic. Dextrans substituted with dyes which bind to nucleic acids were less toxic than the parent dyes themselves; the attachment of such a dye to dextran decreased the binding of dye to cells under detection limits.