L-arginine stimulates host defenses in patients with breast cancer.

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-1β and 2, interferon-γ, and tumor necrosis factor-α were also measured