Vitamin C for all occasions
If you have to defend yourself against an attacker, you should always choose your means carefully. The defender must not be harmed by his own weapon. Immune cells also follow this rule, using harsh chemicals against invading bacteria. Scientists have now found that vitamin C may serve as such a shield, preventing an important type of immune cell from self-destructive. Immune cells called neutrophils destroy the bacteria with the help of a two-stage attack: First, they produce oxidants that puncture the cell wall of a bacterium. In the next step, they devour the now defenseless pathogen. Recent studies by Mark Levine's group at the National Institutes of He alth (NIH) show how neutrophils may avoid poisoning themselves by taking in extra ascorbic acid (vitamin C), which can neutralize oxidants (December issue of Proceedings of the National Academy of Sciences).
To test this theory, a team led by Levine and his colleague Yauhui Wang collected neutrophils from people with bacterial infections. Cells were incubated for up to 1 hour in dishes spiked with vitamin C and nutrients. Some of the bowls were infected with bacteria, the others remained sterile. Within 20 minutes, neutrophils from the infected dishes had accumulated up to 30 times more vitamin C than the cells in bacteria-free dishes. The researchers also found that neutrophils from people suffering from the rare chronic granulomatous disease that makes them particularly susceptible to bacterial infections do not accumulate vitamin C upon contact with bacteria.
Storage of vitamin C "could be a very clever way for neutrophils to protect themselves," says biologist John Curnutte of Genentech, Inc. in San Francisco. However, he and Levine warn that neutrophils may behave differently in the body than they do in the laboratory. The key question, adds cell biologist Sam Silverstein of Columbia University in New York City, is whether increased vitamin C makes a person's neutrophils better bacteria killers. If so, Levine says, then vitamin C would be a simple and safe way to treat strains of bacteria that are resistant to antibiotics.
