Diallyl disulfide reduced dose-dependently the number of lymphocyte subsets and monocytes in rats.

Diallyl disulfide (DADS) is a major sulfur compound of garlic, and exerts anti-inflammatory, immune-modulatory, and enhancing sympathetic activity effects. However, it still remains unclear how DADS affects the distribution of white blood cell subsets, which is essential to execute effective immune responses and partially regulated by adrenal glucocorticoids. Therefore, we examined the dose-dependent effects of DADS administration on the circulating number of white blood cells (WBCs) and lymphocyte subsets, and plasma corticosterone concentration in rats. Male 10-wk-old Sprague Dawley rats were divided into the DADS-free and DADS-orally administered (dose=10, 20, and 40 mg/kg BW) groups. Blood samples were collected from the tail vein at 0, 1, 2, 4, and 6 h after the administration. DADS administration decreased dose- and time-dependently the circulating number of total WBCs, total lymphocytes, and monocytes. Within the lymphocyte subsets, the circulating number of T-lymphocytes and B-lymphocytes was significantly reduced 4 h after DADS administration in a dose-dependent manner, although that of natural killer (NK) cells was not affected. On the other hand, although DADS administration did not significantly change the circulating number of neutrophils, the circulating number of eosinophils and basophils showed a decreasing tendency after DADS administration. In contrast, plasma corticosterone concentration was increased 2 h after DADS administration in a dose-dependent manner. These results suggest that DADS administration reduces the circulating number of monocytes and lymphocytes, including especially acquired immune cells, via the action of corticosterone, and the effects are induced in a dose-dependent manner.