INTERACTION OF AVIDIN-CARRYING RED-BLOOD-CELLS WITH NUCLEATED CELLS

In vivo application of red blood cells (RBC) modified with avidin-biot in complex has been suggested recently for various purposes. However, avidin attachment to RBC alters their biocompatibility. Thus, it has b een described that avidin-carrying biotinylated RBC were lysed by the complement. In the present work interaction between avidin-carrying RB C and nucleated cells has been examined. It was found that attachment of avidin, but not streptavidin, to RBC led to binding of avidin-carry ing RBC to nucleated cells. Adhesiveness of nucleated cells for avidin -carrying RBC varied for different types of nucleated cells. The stron gest adhesion was observed with human fibroblasts and rat Kupffer cell s, while rat liver endothelial cells were practically non-adhesive for avidin-carrying RBC of corresponding species. In contrast with avidin (streptavidin)-induced lysis by the complement, avidin-induced adhesi on was independent of temperature, the presence of divalent ions and m ode of avidin attachment. Polyanions (dextran sulphate and heparin) ef ficiently inhibited the adhesion presumably due to interaction with th e membrane-bound avidin. Polyanions to a much lesser extent inhibited lysis of avidin-carrying RBC, which might be a result of their interac tion with the complement components. Polycations also blocked adhesion of avidin-carrying RBC to nucleated cells, presumably due to interact ion with negatively charged cell-surface components. Therefore, attach ment of avidin to RBC alters their biocompatibility, due to both high positive charge of avidin and the cross-linking of biotinylated membra ne proteins.