Factors affecting the amount and the mode of merocyanine 540 binding to the membrane of human erythrocytes. A comparison with the binding to leukemia cells

Abstract In the presence of albumin Merocyanine 540 (MC540) exhibits a very limited binding to the outer surface of the membrane of normal erythrocytes, whereas pronounced binding is observed to leukemia cells. To find out whether this difference is due to differences in the composition or structural organization of the cell membrane we analyzed effects of a number of covalent and non-covalent perturbations of the red cell membrane on the binding and fluorescence characteristics of membrane-bound MC540. It is shown that exposure of the cells to cationic chlorpromazine, neuraminidase or photodynamic treatment with AlPcS 4 as sensitizer caused a limited increase (30–50%) of MC540 binding, tog…