THE body鈥檚 response to bacterial infection may rely on a newly discovered type of immune cell.
Innate response activator B-cells (IRA-B) release a chemical that rallies neutrophils, immune cells that start attacking and engulfing bacterial invaders.
While neutrophils are at the vanguard of immune defence, the primary role of B-cells was thought to be in organising the later 鈥渁daptive鈥� immune response. This involves producing antibodies tailored to fight specific pathogens, enabling the body to defeat them if they invade again.
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鈥淥ur findings challenge us to revisit this hierarchy,鈥� says of the Center for Systems Biology in Boston, who led the research. 鈥淭his is a cell that plays a key role in the initiation of an immune response, not just in the production of antibodies.鈥�
Swirski and his colleagues discovered the cells when they were looking for the source of a growth factor called GM-CSF that activates other types of immune cell, including neutrophils and macrophages.
They injected mice with a bacterial product to trigger an immune response. When they used a fluorescent antibody that binds to GM-CSF, they spotted its source 鈥� the unusual IRA-B cells, which are produced in the spleen.
The cells also seem to guard against sepsis, a life-threatening immune reaction to infection. Mice engineered to lack functional IRA-B cells were unable to clear bacteria, and died from sepsis (Science, ).
