Stimulation of lymphocyte natural cytotoxicity by L-arginine.

In vitro L-arginine enhanced natural-killer (NK) and lymphokine-activated-killer (LAK) cell activity; this cytotoxicity was mediated by CD56+ cells. In vivo arginine supplements (30 g/day for 3 days) increased the number of circulating CD56+ cells by a median of 32% in eight volunteers (p less than 0.01); this increase was associated with a mean rise of 91% in NK cell activity (p = 0.003) and of 58% in LAK cell activity (p = 0.001) in thirteen volunteers. These findings have potentially important implications for the modulation of natural cytotoxicity in a wide range of disease states.