[L-arginine and immunity. Study of pediatric subjects].

Background: Nitric oxide (NO) play a pivotal role in many biological processes, as in the vessel tone control, the atherogenesis, the platelets aggregation and the immune system modulation. The physiologic precursor of NO is the L-arginine. Evidence exists that the L-arginine administration can stimulate immune system in children with recurrent infections. This clinical trial was designed to evaluate the effects of oral administration of L-arginine on the number of infective events and on the lymphocytes subsets in children suffering from airways recurrent infections.

Methods: Forty outpatients, 21 male and 19 female, aging from 2 to 13 yrs. Two balanced groups, treated for 60 days with L-arginine or a placebo. Evaluation criteria: number of septic episodes; number of circulating white blood cells, % of the lymphocytes; lymphocytes subsets.

Statistical Analysis: Descriptive analysis; inference tests: chi 2; "t" test; variance analysis. Statistical significance: p = 0.05.

Results: Fifteen patients treated with L-arginine and five treated with placebo (p < 0.01) were free from infections. The percentage of CD3 and CD4 subsets significantly (p < 0.05) increased in the L-arginine group than in the placebo group, while the CD8 subset significantly decreased. The CD4/CD8 ratio raised from 1.05 +/- 0.29 to 1.51 +/- 0.46 (p < 0.01) in the L-arginine group, from 1.12 +/- 0.16 to 1.27 +/- 0.24 in the placebo group. There were no side effects in both groups.

Conclusions: L-arginine seems able to increase the immune system defences and to protect against the airway infections.