Human stem cells trigger immune attackJessica Ebert Doubt cast on therapeutic use of embryonic cell lines. Exposure to molecules from animals might have made human stem cells unacceptable.© ANDREW LEONARD / SCIENCE PHOTO LIBRARY Most human embryonic stem-cell lines, including those available to federally funded researchers in the United States, may be useless for therapeutic applications. The body's immune defences would probably attack the cells, say US researchers. When embryonic stem cells are added to serum from human blood, antibodies stick to the cells. This suggests the cells are seen as foreign, and that transplanting them into the body would...