BACKGROUND:

The amino acid L-arginine is known to have immunostimulatory effects in animals and healthy human volunteers. We have studied the effect of dietary supplementation with L-arginine (30 gm/day for 3 days) on host defenses in patients with breast cancer.

METHODS:

Mitogenic responses of peripheral blood lymphocytes to concanavalin A, phytohemagglutinin, and pokeweed mitogen and phenotype analysis of lymphocyte subsets and activation markers were assessed before and after 3 days of L-arginine supplementation. The effect of L-arginine supplementation on natural killer and lymphokine-activated killer cell cytotoxicity and serum levels of the cytokines interleukin-1 beta and 2, interferon-gamma, and tumor necrosis factor-alpha were also measured.

RESULTS:

L-arginine significantly increased lymphocyte mitogenic reactivity to concanavalin A, phytohemagglutinin, and pokeweed mitogen (mean percentage increases: 64% [p < 0.001], 65% [p < 0.001], and 48% [p < 0.05], respectively). Natural killer and lymphokine-activated killer cell cytotoxicity was also significantly enhanced after L-arginine intake (mean percentage increase, 81% and 107% [p < 0.001]). However, no corresponding increase in circulating CD16+ and CD56+ cells was obtained: Arginine supplementation did not increase the level of serum cytokines.

CONCLUSIONS:

Dietary supplementation with L-arginine in patients with breast cancer significantly enhances host defenses and therefore may have a role in adjuvant treatment.