The Effect of Restricted Dietary Intake on the Antibody Mediated Response of the Zinc Deficient A/J Mouse

Abstract

The objective of the present study was to determine whether or not dietary restriction was an important factor in the previously observed thymic atrophy and impairment of T-cell helper function which accompanies a deficiency of zinc in the young adult A/J mouse. Accordingly, two separate experiments were conducted using 5-week old female mice which were individually fed according to the following protocol: 1, a group fed the zinc deficient diet (0.5–0.6 µg/g Zn); 2, a group fed the zinc supplemented diet (50–60 µg/g Zn), but their intake was restricted to the average daily amount consumed by the zinc deficient group and 3, a group fed the zinc supplemented diet ad libitum. All mice were immunized with sheep red blood cells (SRBC), and the response to the antigen was measured by the Jerne plaque assay. In the first experiment covering a period of 28 days the dietary restriction had no significant effect on the antibody mediated immune response. However, the zinc deficient mice were found to have a pronounced loss in immune capacity. The second experiment was extended to a 32-day feeding period and the zinc deficiency symptoms produced were more severe, and the reduction in diet intake was greater than that produced in the first experiment. Under these conditions, the inanition affected the thymus weight and plaquing capacity. The results indicate that while zinc deficiency per se does cause a loss of immunity, the severe dietary restriction imposed by prolonged feeding of a zinc deficient diet will also contribute significantly to this loss.