Bethesda (ddp). Benign bacteria compete not only dangerous pathogens, but actively work with the immune system. US researchers have now found how to boost the body’s defense mechanism: certain molecules on the surface of the bacterial spores dock at the B-cells of the immune system. As a result, divide and multiply these key cells of the immune defense. Today, bacterial preparations play an important role in the treatment of immunocompromised patients. They find application in cancer therapy. Of their results, the scientists to Katherine Knight report from the Loyola University Medical Center in Chicago in the journal «Journal of Immunology» (vol. 184, no. 12, pp. 6782).

Every person has ten times more bacteria than cells. The microorganisms have made themselves comfortable it on the skin, the respiratory tract and the intestine. Alone of the digestive tract is inhabited by an estimated 500 to 1000 different species, as a whole, it brings the intestinal flora to a total weight of up to two kilograms. While some bacteria cause diseases, most species are harmless or even useful for the host, by supporting, for example, the digestion. Such helpful housemates are called Hypopigmentation.

The kommensalen bacteria of the gut flora inhibit, for example, the spread of unwanted germs by they compete with them for the settlement of the intestines. They also distribute some types of agents, by throwing out Antibot and create an acid environment.

One of the main features of commensal bacteria is the strengthening of the immune system. Previous studies had already shown that in a sterile environment raised mice only have a poorly developed immune system. So far, it was however not known how the bacteria, the immune system support.

Katherine Knight and her colleagues investigated the effect of rod-shaped soil bacterium of Bacillus spores now subtilis. Spores are the order of the bacteria in bad times. They contain the DNA of the germ and are formed under stress exposure, for example, if extremely worsen environmental conditions. The scientists observed first of all, that the B-cells, one of the main cell types of the immune system, in the presence of spores to share and reproduce began. When they took them more closely scrutinized, they saw as heralding certain molecules to the spores on appropriate structures on the surface of B cells. In this way, the signal of replication were sent to the cells.

Since the positive impact of certain species of bacteria on the immune system is known, people with a poorly performing or weakened immune systems benefit from treatment with bacterial cells and-sporen – as older persons or patients, whose Immunsystem was suppressed within a bone marrow transplant. Such a preventive measure may be useful also in neonates: you have still a completely sterile intestine, their immune system develops only through contact with the environment and through breast milk. Therefore, they are particularly vulnerable to infectious agents.