BETHESDA, MARYLAND. The body's defense system against bacterial infections relies heavily on the action of neutrophils, a key type of immune cells. Neutrophils destroy bacteria by first producing oxidants which puncture the bacteria's cell walls and then complete the job by gobbling up the bacteria. Researchers at the National Institutes of Health now report that vitamin-C (ascorbic acid) may play a key role in protecting the neutrophils from poisoning themselves during their battle with the bacteria. The researchers incubated neutrophils in two sets of dishes containing nutrients and vitamin C. One set of dishes contained bacteria (E.coli and others) or fungi (Candida albicans) while the other, the control, was free of bacteria and fungi. When measuring the ascorbate concentration in the neutrophils after 45 minutes of incubation the researchers discovered that the neutrophils which had been exposed to bacteria or fungi contained 30 times more ascorbate than did the neutrophils which had not been exposed. The ascorbate level in the neutrophils was found to increase as the ascorbate concentration in the nutrient solution increased; however, the ascorbate level within the bacteria and fungi did not increase even at high extracellular ascorbate concentrations. The researchers conclude that infectious bacteria and fungi induce neutrophils to recycle spent ascorbic acid at a vastly accelerated rate and thereby increase the concentration inside the neutrophil. They speculate that these higher ascorbate concentrations within the neutrophils help to protect them against free radicals developed in the battle with the bacteria. No in vivo experiments have been done so far, but the researchers conclude that it may be worthwhile to do further research into the potential application of vitamin C supplementation in combating bacterial and fungal infections especially infections involving antibiotic-resistant bacteria.
Wang, Yaohui, et al. Ascorbate recycling in human neutrophils: induction by bacteria. Proceedings of the National Academy of Sciences USA, Vol. 94, No. 25, December 9, 1997, pp. 13816-19