CAMBRIDGE, Mass. (July 9, 2007) Biology textbooks are bluntneutrophils are mindless killers. These white blood cells patrol the body and guard against infection by bacteria and fungi, identifying and destroying any invaders that cross their path. But new evidence, which may lead to better drugs to fight deadly pathogens, indicates that neutrophils might actually distinguish among their targets.
A scientist in the lab of Whitehead Member Gerald Fink has discovered that neutrophils recognize and respond to a specific form of sugar called beta-1,6-glucan on the surface of fungi. This sugar comprises just a small fraction of the fungal cell wall, much less than another sugar with a slightly different chemical conformation called beta-1,3-glucan. Because the scarce form of the sugar elicits a much stronger reaction from immune cells than the abundant one, it appears that neutrophils can distinguish between two nearly identical chemicals.
These results show that engulfment and killing by neutrophils varies, depending on cell wall properties of the microbe, explains Whitehead postdoctoral researcher Ifat Rubin-Bejerano, first author on the paper, which appears July 11 in the journal Cell Host & Microbe. We showed that neutrophils respond in a completely different way to slight changes in sugar composition. If we are able to use this unique sugar to excite the immune system, it may help the human body fight infection.
Previously, everyone thought that these key cells of the immune system weren't picky and would eat anything that looked foreign, adds Fink, who is also an MIT professor of biology. Ifat's work has shown that the cells aren't little Pac-Men, but can discriminate one pathogen from another.
Rubin-Bejerano had evidence that neutrophils respond to beta-glucan. After coating tiny beads with a variety of substances (including beta-1,3-glucan and beta-1,6-glucan), she exposed them to the neutrophils and was surprised to see
Contact: Alyssa Kneller
Whitehead Institute for Biomedical Research