A rare group of white blood cells called basophils play an important role in the immune response to a bacterial infection, preventing sepsis from developing, researchers from Seattle Children's Research Institute report in Nature Immunology.
To better understand the changes the immune system has as an infection progresses into sepsis, the researchers tracked the immune response to the early stages of infection.
They looked at a specific group of white blood cells called basophils, which are known to help start an immune response to an infection.
"As one of the rarest cell types in the body, basophils make up less than 1 percent of a person's white blood cells," said Adrian Piliponsky, PhD, a principal investigator in the research institute's Center for Immunity and Immunotherapies. "Scientists have long suspected that basophils can enhance the immune defense against a bacterial infection although there was no scientific proof of this role prior to our study."
To assess how basophils contribute to the immune response, the researchers used a model of bacterial infection and sepsis that resembles the progression and characteristics of human sepsis in genetically modified mice.
They found basophils were one of the first types of immune cell to appear at the infection site. The basophils enhanced inflammation at the early stages of an immune response to infection and improved survival in mice, doing so in part by releasing a protein called tumor necrosis factor.
The protein sends a signal to other cells that helps generate the inflammatory response for protecting and healing damaged tissue. Its presence in the study adds to growing evidence that basophil-derived tumor necrosis factor plays a key part in the first stages of the immune system's defense against an infection, and shows that a lower basophil presence can lead to sepsis, the researchers said.
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