Influence of graded magnesium deficiencies on white blood cell counts and lymphocyte subpopulations in rats.

Increased white blood cell counts or leukocytosis have been observed primarily in young rats fed diets extremely low in Mg (< 60 ppm) and high in phosphorus (0.5 % P). We investigated the influence that acute and moderate Mg deficiencies have on blood leukocytes at high and low dietary phosphorus levels. For four weeks, male Sprague-Dawley rats (initially 7 weeks old) were fed diets containing 30, 60, 120, 208, or 850 ppm Mg and either 0.3 % or 0.5 % dietary phosphorus. Total leukocytes were increased in rats fed 30 ppm Mg (p < 0.0001), and the leukocyte subpopulation counts of lymphocytes, neutrophils, monocytes and eosinophils increased significantly only in the rats fed 30 ppm Mg (p < 0.0001). B-cells decreased significantly as a percentage of lymphocytes (p < 0.0093) as dietary Mg decreased. As total counts in blood, B-cells, CD4 and CD8 cells were significantly increased in the rats consuming the 30 ppm Mg diet. Dietary phosphorus only had an effect in combination with the lowest dietary Mg. These results demonstrate a threshold effect for increased leukocytes during a Mg deficiency of four weeks. A Mg deficiency of a longer duration may show different results.