Metrizamide density gradients for separation of different developmental stages of malarial parasites.

Density gradients with metrizamide, a tri-iodinated benzamido derivative of glucose, have been used to separate erythrocytes infected with three species of murine plasmodia. Uninfected erythrocytes separated well from erythrocytes containing parasites in different developmental stages. With metrizamide solutions, the densities required for isopyknic separation can be obtained without hypertonicity or high viscosity, and the viability and metabolism of parasites and erythrocytes are not detectably modified by exposure to these solutions. This type of separation has many possible applications to biochemical and immunological investigations.