Zinc is known to play an important role for immune-functions. However, the effects of zinc-deficiency on the immune response system from the point of view of the distribution changes of the number of total white blood cells (WBCs) are still primarily unknown. Therefore, the effects of zinc-deficiency on the number of total WBCs, neutrophil, eosinophil, basophil, monocyte and lymphocytes (T lymphocyte, B lymphocyte and NK cell) were studied in rats. The weaned male rats were randomly divided into the zinc deficient diet (ZDD: 0.7 mg zinc/kg diet) group and the control diet (CON: 34.8 mg zinc/kg diet) group, and were pair-fed for 4 wk. The number of lymphocyte subsets, visceral organ weights, serum zinc, corticosterone and IL-6 concentrations were also determined. Zinc-deficiency increased duration-dependently the number of total white blood cells, granulocytes (neutrophil, eosinophil and basophil) and monocytes in 2-4 wk without changing the number of lymphocytes, T lymphocytes, B lymphocytes or NK cells. The relative weights of thymus and adrenals were 0.63 times (p<0.01) lower and 1.60 times (p<0.001) higher in ZDD group than in CON group, respectively. Zinc-deficiency increased serum corticosterone concentration to 1.48 times (p<0.05) without changing serum IL-6 concentration, as compared with those of CON group. From these results, zinc-deficiency increases markedly the number of granulocytes and monocytes without changing the number of lymphocytes, T lymphocytes, B lymphocytes or NK cells. These results also suggest that zinc-deficiency induces stress responses and the responses may have in part participated in increased actions of the number of granulocytes and monocytes during zinc-deficiency, and induce thymus atrophy and adrenal hypertrophy.
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