Dying parasites as "door opener"

Altruism paves the way for infections

Leishmaniasis parasites CDC
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Our immune system detects and kills most microorganisms. Nevertheless, some parasites manage to infect body cells, even cells of the immune system. Researchers at the University Hospital Schleswig-Holstein have now investigated how and why these pathogens can infect cells using the example of the tropical disease leishmaniasis. They came to a surprising conclusion: Dying parasites clear the way for infections.

50, 000 people in Africa, Asia and South America are the victims of leishmaniasis each year, with 500, 000 new cases and a global threat of 350 million people.

The infectious disease is transmitted through the bite of a sandfly on parasites on humans. In the latest issue of the journal "Proceedings of the National Academy of Sciences USA" (PNAS), the Lübeck researchers report that not only living Leishmania are transmitted through the saliva of the sandfly, but also so-called "apoptotic" parasites. These are cells where genetic programs have led to "suicide" in a well-defined manner.

Organism becomes "silent" infected

Such cells are normally taken up and dissected by the cells of the infected organism. The new discovery of the Lübeck researchers is that the dead parasites fulfill an important function even in death: they give the living microorganisms the way into special white blood cells, the granulocytes. These important body cells would normally recognize the living parasites as foreign bodies and kill them immediately.

However, because dead leishmania are present at the same time, the granulocytes can not recognize the parasites as foreign and harmful and therefore do not react. From the point of view of the pathogens, this newly discovered mechanism is a welcome opportunity to infect the organism "silently". display

(idw - University Hospital Schleswig-Holstein (UK SH), 21.09.2006 - DLO)