Effect of Antioxidants on Immune Responses under Conditions of Additional Respiratory Resistance

INTRODUCTION: Additional respiratory resistance causes fatigue of the respiratory muscles and acts an as immune stimulus. Oxidative stress associated with the work of respiratory muscles, is one of potential modulators of the immune response. AIM: To study the effect of antioxidants on the immune response under conditions of additional respiratory resistance. MATERIALS AND METHODS: Twenty-six healthy subjects performed two 5-min resistive breathing sessions at 70% of maximal mouth pressure (Pmmax) before and after administration of antioxidants (vitamins E, A, C within 60 days), respectively. Blood sampling was performed before each session of resistive breathing and immediately upon its completion. Subpopulations of lymphocytes were determined by flow cytometry. Lipid peroxidation indices were determined using biochemical methods. RESULTS: Resistive breathing was accompanied by increase in T lymphocytes mainly due to T helper cells, upon that, the subpopulation of natural killer cells significantly increased, while cytotoxic fraction of T lymphocytes decreased providing a significant increase in the immunoregulatory index (CD4+/CD8+). A six-month course of antioxidant therapy in the form of a combination of vitamin E, vitamin A and vitamin C reliably reduced the effects of resistive breathing affecting changes in the subpopulations of lymphocytes, reduced the lipid peroxidation indices (levels of free fatty acids, hydroperoxides and malondialdehyde) and increased the antioxidant activity indices (levels of catalases and total antioxidant activity). Resistive breathing induced changes in the subpopulations of lymphocytes through an oxidative stress-dependent pathway. CONCLUSION: Inspiratory resistive breathing causes changes in the subpopulations of peripheral blood lymphocytes. A six-month course of antioxidant therapy of lymphocytes significantly mitigates changes in the subpopulations of lymphocytes, reduces the lipid peroxidation indices and increases the antioxidant activity indices. Oxidative stress mediates changes in the subpopulations of lymphocytes after resistive breathing.