PHOTOHEMOLYTIC LESIONS: STOICHIOMETRY OF CREATION BY PHLOXINE B

The uptake of the halogenated fluorescein sensitizers, Rose Bengal and phloxine B, by erythrocyte membranes was measured as a function of incubation time. Ghost membranes concentrate the sensitizers to levels greatly in excess of the sensitizer concentration in the suspension medium. Most of the uptake occurs in the first hour and is virtually complete by four hours. It is not significantly affected by stirring under the present conditions. The distribution of sensitizer cannot be explained as partitioning between immiscible solvents. Rather the data fits the Freundlich adsorption isotherm over a wide range of sensitizer concentrations and ghost protein values. Photohemolysis experiments were performed using sensitizer concentrations and incubation times similar to those used in the sensitizer uptake studies. The kinetics of lysis were found to vary with the 1.2 power of sensitizer concentration using PB. When combined with the uptake data for this sensitizer, these results imply that photohemolytic lesions in the red cell membrane are formed by the action of two sensitizer molecules.