During her doctoral research, Desiree van der Kleij discovered that lipids from the parasite schistosoma steer the development of the immune system in a certain direction. Cells from the innate immune system, so-called dendritic cells, respond to these lipids. During this response these cells can initiate the development of so-called regulatory T-cells. These regulatory T-cells subsequently suppress the activity of other cells in the immune system.
The researcher discovered that one of the lipids with this steering effect on dendritic cells contains a fatty acid that does not occur in humans. She also demonstrated that this specific lipid of the parasite activates a specific receptor on dendritic cells. Once the receptor had been blocked, it was found that regulatory T-cells no longer developed after dendritic cells had been stimulated with the parasite lipid.
Diseases such as diabetes and asthma are caused by inappropriate immune responses to certain substances. Molecules which can inhibit the immune responses, such as the lipids of schistosomes, could be used to suppress these errant responses. The use of lipids from schistosomes for this purpose will be investigated in a follow-up study funded by the Netherlands Organisation for Scientific Research.
In the immune system, dendritic cells detect the presence of pathogens in the body. These cells then direct the development of immune responses so that a type of immune response develops which is appropriate to combat the pathogen present. The pathogen could be a bacteria, but equally a virus or a parasite.
Schistosomes are parasitic worms. More than 200 million people worldwide are infected with the worm. The majority of these people live in Africa and South America. The worms can survive in their host for years. Although infected persons develop an immune response during an infection, the parasite significantly suppresses the activity of the immune system in people who are chronically infected with these worms. This suppression is probably caused by regulatory T-cells.
For further information please contact Dr Desiree van der Kleij (Department of Parasitology, Leiden University Medical Center), tel. 31-71-526-5066, e-mail: d.van_der_kleij@lumc.nl. The doctoral thesis was defended on 5 November 2003 at Leiden University. Dr Van der Kleij's supervisors were Prof. A.M. Deelder (Leiden University Medical Center) and Prof. A.G.M. Tielens (Utrecht University) and her assistant supervisor was Dr M. Yazdanbakhsh (Leiden University Medical Center).
The research was funded by the Netherlands Organisation for Scientific Research.