The kinetics of colloid osmotic hemolysis. II. Photohemolysis.

Many of the known features of photohemolysis have been organized in a kinetic model that simulates the lytic time-course in a variety of conditions. The model combines Nernst-Planck flux principles, the osmotic equilibrium model of Freedman and Hoffman, equations relating illumination parameters to ion permeability, and an empirical relation between cell volume and lysis. Model simulations are compared with experiments showing the dependence of lysis kinetics on sensitizer concentration and on the osmotic content of the reaction medium. Additional experiments demonstrate that the inherent osmotic fragility of erythrocytes is not altered by illumination conditions that cause major delayed lysis 23 h later. The successful simulations support the hypothesis that photohemolysis is a colloid osmotic lysis occurring in cells behaving as imperfect osmometers.