['Arginine deficiency and chronic inflammation may cause immune dysfunction. The authors previously showed that a pharmacological dose of parenteral arginine facilitates ornithine rather than nitric oxide production in subacute peritonitis. Herein, they investigated the effects of different doses of parenteral arginine supplementation on immunocytic subpopulation distribution and function.', 'Male Wistar rats that underwent cecal punctures for induction of subacute peritonitis were infused with conventional parenteral nutrition solution (1.61% of total calories as arginine) or solutions supplemented with low-, medium-, or high-dose arginine (2.85%, 4.08%, and 6.54% of total calories, respectively) for 7 days. Distributions of T cells, B cells, and monocytes/macrophages and cytokine productions of peripheral blood lymphocytes (PBLs) and splenocytes were analyzed.', 'There were no significant differences in circulating white blood cell numbers and serum tumor necrosis factor (TNF)-α and interferon (IFN)-γ concentrations among groups. Serum nitrate/nitrite (NOx) and interleukin (IL)-2 levels were significantly decreased by arginine in a dose-dependent manner. Animals supplemented with parenteral arginine had significantly decreased productions of concanavalin (Con) A- and lipopolysaccharide (LPS)-stimulated TNF-α in PBLs and splenocytes, spontaneous IL-6 and LPS-stimulated IFN-γ in PBLs, and LPS-stimulated IL-6 in splenocytes. In addition, low-dose arginine significantly increased production of spontaneous IFN-γ in PBLs and splenocytes. High-dose arginine significantly increased spontaneous TNF-α, and Con A stimulated IL-4 and IL-6 in PBLs.'] Does appropriate dose of parenteral arginine enhance immunity of peripheral blood cells and splenocytes in rats with subacute peritonitis?