Because the microbiota is so complex, containing hundreds of different bacterial species, it was not known how the presence of microbes in the intestine shaped the antibodies that are present even before we are challenged by an infection. Researchers have now shown how beneficial microbes reprogram white blood B cells that produce antibodies and how this helps counter infections.
In a research article published in the journal Nature, a European research team analyzed billions of genes that code the antibodies in a system that allows the responses to individual benign intestinal microbes to be understood.
B cells are white blood cells that develop to produce antibodies. These antibodies, or immunoglobulins, can bind to harmful foreign particles (such as viruses or disease-causing bacteria) to stop them from invading and infecting the body's cells.
Intestinal microbes trigger expansion of B cell populations and antibody production, but until now it was unknown whether this was a random process, or whether the molecules of the intestinal microbes themselves influence the outcome.
Researchers used specially designed computer programs to process millions of genetic sequences that compare the antibody repertoire from B cells, depending on whether the microbes stay in the intestine, or whether they reach the bloodstream. In both cases the antibody repertoire is altered, but in rather different ways depending on how the exposure occurs.
"Interestingly, this is rather predictable depending on the microbe concerned and where it is in the body, indicating that the intestinal microbes direct the development of our antibodies before we get a serious infection and this process is certainly not random," explains Dr. Ganal-Vonarburg.
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