Blood Transfusion Scrapie?
Swiss scientists have discovered that certain types of white blood cells play a role in the development of scrapie. Scrapie is a prion-induced disease discovered in sheep, adding new fuel to the discussion about the safety of blood products, the researchers said. Since the discovery of prions, the question has repeatedly arisen as to whether prion infection can be transmitted through blood. This suspicion was reinforced when it became apparent that the lymphatic system, including the tonsils, thymus, lymph nodes and spleen, could serve as a reservoir for the development of pathogenic prions prior to actual infection. The white blood cells (lymphocytes) also develop in the central lymphatic organs.
Adriano Aguzzi and his colleagues from the University of Zurich have now discovered in an animal experiment that mature B lymphocytes play a crucial role in the development of scrapie (Nature, December 18, 1997). The scientists studied different strains of mice suffering from different immune system deficiencies to determine which cells or parts of the immune or blood systems infect the nerves.
It turned out that all the mutations that prevent the development of B lymphocytes also protected the test animals from scrapie. If there is a lack of these white blood cells, it is not only the nervous system that remains undamaged. When the scientists injected the mice with infectious tissue from animals containing scrapie, they found no prion contamination in the spleen. It appears that all types of B lymphocytes are involved in the infection process, no matter what types of antibodies they produce. According to the researchers, "The results suggest that B lymphocytes may transport prions from the lymphoid organs to the nervous system."
Although an involvement of B lymphocytes in other prion diseases has not yet been proven, the question arises to what extent the research results should be taken into account in the commercial production of blood products. New study supports voices calling for white blood cells to be removed from related products.
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