Magnetophoresis: II. Quantification of iron and hemoglobin content at the single erythrocyte level

The iron and hemoglobin content of individual erythrocytes was determined using a method based on parallel velocity measurements during magnetophoresis and gravitational sedimentation of individual erythrocytes in suspension. In previous publications we have suggested employing cell magnetophoresis, a biophysical phenomenon characterized by cell movement in a fluid under magnetic field influence, for cytometry. The paramagnetic ferric iron in methemoglobin is used as a magnetic label. The iron content is estimated from the magnetophoresis velocity, and hemoglobin content from the gravitational sedimentation velocity of erythrocytes. Blood samples are also analyzed in a Coulter counter to determine their mean corpuscular hemoglobin. The time course of the reaction of methemoglobin reduction is quantified at the single erythrocyte level. The methemoglobin content in individual erythrocytes is determined following the oxidation reaction. Erythrocytes from patients with normo-, hypo-, or hyperchromic anemia exhibit magnetophoresis and gravitational sedimentation velocities that correlate closely with mean corpuscular hemoglobin. We propose the utilization of magnetophoretic cytometry for detailed diagnostic studies at the single erythrocyte level. Furthermore, the magnetophoresis velocity to gravitational sedimentation velocity ratio is proposed as a standard value for comparative study of magnetically labeled cells in future investigations, as it was found to be constant and independent of hemoglobin content.