Lethal Factor, one of three poisonous proteins in the anthrax bacterium, disables dendritic cells - which form a crucial part of the immune system - effectively preventing an attack against the anthrax microbe.
This is the first study that demonstrates any interaction between bacillus anthracis (anthrax) and dendritic cells, said Dr Bali Pulendran of Emory University in Atlanta, Georgia, on Wednesday.
"When dendritic cells are compromised, such as in our study...the innate immune system is unable to stimulate the immune response, thus permitting the microbe to spread unchecked," he added. The study was published in the science magazine “Nature”.
The ultimate goal is to apply the discovery to develop better anthrax treatments and to shape future research into controlling immune responses more appropriately, Pulendran said.
Lethal factor and two other toxins, protective antigen and edema factor, increase the deadly potency of anthrax, which killed five people infected by tainted letters in a bio-attack scare in the United States nearly two years ago.
The edema factor causes the release of fluid into the lungs and is deadly on its own. Protective antigen shields the other two toxins from the immune system, allowing them to enter target cells, and lethal factor destroys immune system cells.
When the cells die, they trigger a reaction in the body that can cause septic shock and death.