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Objective: Previous studies have shown that leucocytes, in particular granulocytes, have an enormous capacity for reactive oxygen species (ROS) production, and that this can be influenced by the physical activity of the individual. Theoretically, endurance-trained athletes could profit by increasing their intake of antioxidants, thus neutralizing increased ROS production. The aim of the present investigation was to study the effect of dietary antioxidant supplementation on leucocyte ROS expression and total plasma antioxidant status (TAS) in endurance-trained athletes over the course of 4 weeks., Methods: Eighteen athletes were recruited for the study. A randomized, double-blinded, placebo-controlled crossover study of 4 weeks of antioxidant supplementation (BiO-Antioxidant 2.1 (400 mg vitamin C and 180 mg vitamin E d(-1)) and BiO-Quinon Q10 (200 mg d(-1) was performed. Flow cytometry was applied to examine the leucocyte expression of ROS using the ROS-sensitive probes dihydroethidium and dihydrorhodamine 123. The Randox Total Antioxidant Status kit was used to measure the plasma TAS of the athletes., Results: After 4 weeks of antioxidant supplementation, we observed no significant differences in ROS levels in granulocytes and monocytes either basally or after in vitro stimulation with phorbol myristate acetate. Plasma TAS did not change significantly during the intervention period., Conclusions: We observed no influence of 4 weeks of dietary antioxidant supplementation on oxidative stress status. Based on these findings, there is no rationale advising athletes to ingest antioxidant supplements in addition to their regular diet if that includes daily recommended doses of vitamins.

Unlabelled: To elucidate the pathophysiology of infections with Streptococcus pyogenes we applied flow cytometric techniques to study dose-response and time-related effects of the streptococcal cell-wall-derived components lipoteichoic acid (LTA 0.005 to 50 microg/ml) and peptidoglycan (10 and 100 microg/ml) on the expression of leukocyte adhesion molecules, the CD14 receptor, and the production of leukocyte reactive oxygen species (ROS). LTA (50 microg/ml, 1-2 h) markedly increased the expression of CD11b (approximately 5-fold), CD11c (approximately 2-fold) and CD11a. Concomitantly, CD62L was downregulated (60%). Peptidoglycan alone or in combination with LTA had little effect on adhesion molecules, except for an amplification of the downregulation of CD62L to 90%. Monocyte CD14 expression was doubled by LTA. Leukocyte ROS production was 10-fold and 5-fold increased by peptidoglycan in granulocytes and monocytes, respectively. LTA alone had no effect, while the combination of peptidoglycan with LTA doubled the increase in ROS caused by peptidoglycan., Conclusion: LTA and peptidoglycan had marked and differential effects: LTA caused mainly adhesion molecule modulation, whereas peptidoglycan mainly increased ROS production. These changes are important in inflammatory cell activation and recruitment, intracellular microbial killing and adverse tissue injury.