Simultaneous studies were made as to the degrees of Heinz body formation, of change in hemoglobin and of change in osmotic fragility in erythrocytes incubated with certain drugs which are known to produce Heinz bodies in vivo. Certain factors that modify the pattern of effect of drugs on normal adult erythrocytes were also studied.
A close relationship was found between the degrees of Heinz body production and "intact" hemoglobin destruction. Factors that caused variation in the degree of "intact" hemoglobin destruction caused similar variation in the degree of Heinz body production. Staining studies suggested that Heinz bodies are protein in nature and derived from hemoglobin. These observations were taken to indicate that Heinz bodies probably result from the direct effect of certain drugs on intra-erythrocytic hemoglobin.
β-naphthol and primaquine were found to cause marked increase in osmotic fragility relative to the degrees of Heinz body production and of "intact" hemoglobin destruction, whereas acetyl phenylhydrazine produced marked Heinz body production and "intact" hemoglobin destruction with relatively little increase in osmotic fragility. These observations were regarded as evidence that Heinz body production is not the sole determinant of instability of erythrocytes exposed to these various drugs.
Under no experimental conditions was Heinz body production or "intact" hemoglobin destruction found without methemoglobin formation. Evidence was presented to indicate that Heinz body production could be inhibited by trapping methemoglobin as methemoglobin cyanide or methemoglobin azide. The suggestion was advanced that methemoglobin is in fact an essential stage in the destruction of "intact" hemoglobin and the formation of Heinz bodies.