Fast, stable method for harvesting leukocytes for measuring intracellular magnesium.

A new method for isolating blood leukocytes and measuring intracellular leukocyte magnesium is based on three successive centrifugations (1300 x g, 5 min, 22 degrees C), with no use of Ficoll, followed by two washes. We express the leukocyte magnesium concentration in micromoles of magnesium per gram of protein. Magnesium is measured by atomic absorption spectrophotometry, protein by the classic Lowry method. With the method 8% to 28% of the leukocytes are isolated and 0% to 0.025% of the erythrocytes. Of the isolated leukocytes 86% to 93% are viable. The magnesium concentration is constant at centrifugal forces greater than 1000 x g, at a centrifugation time of 5 to 15 min, and with use of two or three washes. However, the cells lose 1% of their magnesium content per hour when samples are left at 22 degrees C. The temperature influences this. In blood samples from 98 volunteer blood donors, mean leukocyte magnesium concentrations were 26.4 (SD 3.9) mumol/g. There was no significant correlation between the magnesium concentration and the relative amount of neutrophils.