Page 1352 - Veterinary Immunology, 10th Edition

during infections. Copper deficiencies are also immunosuppressive.
VetBooks.ir Thus a copper deficiency reduces neutrophil numbers and function

by depressing superoxide production. It also reduces lymphocyte
responsiveness to mitogens; reduces T, B, and NK cell numbers;

and enhances mast cell histamine release. Selenium deficiency
depresses the function of most immune cells, reducing neutrophil,
T, and NK cell responses, and IgM production. Supplementation
with selenium upregulates the expression of IL-2R and prevents

oxidative damage to immune cells. Iron deficiency is
immunosuppressive for cell-mediated responses. However, the
effects of this on resistance to infection are complex since many
pathogens require iron to replicate (Chapter 7). Magnesium

deficiency reduces immunoglobulin levels.

Vitamins

Three vitamins, A, D, and E, are critical for proper immune
function. If a pregnant animal is vitamin A deficient, its lymphoid
tissue development is impaired. Deficiencies of vitamin A reduce

lymphocyte proliferation, NK cell activity, and cytokine and
immunoglobulin production (Fig. 40.8). Some vitamin A
metabolites such as retinoic acid enhance T cell proliferation and

cytotoxicity. Retinoic acid is especially important in promoting Th2
and dendritic cell differentiation in the intestine and in the homing
of IgA-positive B cells to mucosal surfaces. It also maintains Treg
and ILC3 levels in the intestinal mucosa and thus regulates
tolerance to food antigens (Chapter 21).

1352