Abstract
The role of cell surface coating materials on concanavalin A (ConA)-mediated red blood cell (RBC) adsorption was investigated to clarify the molecular basis of the aging- and transformation-associated changes in RBC adsorption. The RBC adsorption with the RBC coating method (in which ConA-coated RBCs are adsorbed to fibroblasts) was enhanced by neuraminidase and trypsin treatments of RBCs, and by neuraminidase, hyaluronidase, chondroitinase ABC, collagenase and trypsin treatments of fibroblasts. Protamine and poly- l-lysine also enhanced the RBC adsorption with this method. In addition, the younger the cells, the greater the extent of the increase in RBC adsorption with all these treatments. On the other hand, the RBC adsorption with the fibroblast coating method (in which RBCs are adsorbed to ConA-coated fibroblasts) could not be enhanced by neuraminidase or trypsin treatment of RBCs, or by neuraminidase, hyaluronidase or chondroitinase ABC treatment of fibroblasts to a significant degree. Only trypsin and collagenase treatments of fibroblasts enhanced the RBC adsorption with the fibroblast coating method. The RBC adsorption was also enhanced by urea and cytochalasin B (CB), but not by phorbol myristate acetate (PMA) or tunicamycin. The results of 125I-cell surface labelling indicated that the amount of 220 000 molecular weight major cell surface protein decreased in senescent and 60Co- and SV40-transformed cells. In addition, the enzymes and drugs which increased the RBC adsorption with the fibroblast coating method were those which decreased this protein. These findings suggest that the different results in RBC adsorption associated with aging and transformation with the RBC and fibroblast coating methods can be explained in terms of the large major cell surface protein and surface negative charges.
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