Depressed immune response in the magnesium-deficient rat.

The effects of dietary magnesium on growth, food efficiency, organ development, splenic nucleic acids, and serum antibody were studied in two experiments with male Wistar rats. Diets containing 30% protein from casein were fed ad libitum. Rats were immunized intravenously with sheep red blood cells. Blood was obtained 5 and 9 days after immunization. In experiment 1, a group of weanling rats was fed 10 ppm Mg for 8 days, followed by 142 ppm for 37 days. Group 2 (controls) was fed 480 ppm Mg for 45 days. Group 1 weighed less but had larger spleens, kidneys, and testes relative to body size than did group 2. Nucleic acids per gram spleen were similar in both groups as were serum gamma-globulin and its 19S and 7S components. Antibody log titers for group 1 were 45 and 65% of control agglutinin levels and 44 and 80% of control hemolysin values on days 5 and 9, respectively. In experiment 2,200-g rats were fed 10 (group 3) or 480 ppm (group 4) Mg for 38 days. Most effects of the 10 ppm Mg diet were similar to those seen in magnesium deficiency in experiment 1. Antibody titers for group 3 were 30 and 25% of control agglutinin and 43 and 53% of control hemolysin values on days 5 and 9, respectively. Total serum gamma-globulin and its 19S fraction were similar in both groups, while the 7S fraction of group 3 was only 64% of the control value.