The purpose of this study was to study the effects of L-arginine on the clinical course and some immunological parameters in patients with asthma. Material and Methods: In this study, we examined 56 patients with moderate and severe persistent asthma. The duration of the disease ranged between 15+2. 3 years. The patients were divided into two groups. The patients of the study group (n=25) were subjected to the standard treatment and nitric oxide (NO) donor L-arginine. The patients of the

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... son group (n=31) received the standard treatment only. All patients underwent a complete physical examination including a determination of serum cytokine levels (IL-4, IL-8, and TNF-α) both prior and post treatment. Results: In both groups, the baseline serum levels of IL-4, IL-8 and TNF-Fα were greater than the normative values. Direct correlations were observed between the level of the interleukins and clinical symptoms. Daily intravenous infusion of L-arginine at 4.2 g for 30 min over 10 days significantly reduced the serum levels of IL-4, IL-8 and TNF-α. No significant changes were noted in the levels of these parameters in the control group. Conclusion: The addition of L-arginine to the basic treatment in asthmatic patients contributed to the earlier improvement of clinical symptoms and a significant reduction of the IL-4, IL-8 and TNF-α serum levels.