1. Treatment of normal human red cells with various proteolytic enzymes, cholera vibrio filtrate, influenza virus, and periodate ion results in red cells susceptible to acid hemolysis in compatible normal human serum.
2. The kinetics of hemolysis of these artificially altered red cells resembles in many respects those observed in paroxysmal nocturnal hemoglobinuria (PNH).
3. While the observed differences in behavior between these artificially altered cells and PNH cells do not allow direct comparison, it is felt that these models may offer some clues in the understanding of PNH cell hemolysis, and some insight into the nature of the red cell lesion in paroxysmal nocturnal hemoglobinuria.