RAT CELLS’ immune response has been switched on and off with a magnetic field – a technique that could control treatment of allergies and other illnesses more precisely.

Donald Ingber’s team at the Children’s Hospital in Boston created iron nanobeads that bind to receptor molecules on the surface of immune cells taken from rats. When exposed to a magnetic field, the beads cluster together, pulling the receptors with them. Changes to the receptors due to aggregation set off a series of chemical reactions that trigger the cell’s immune response (Nature Nanotechnology, DOI: 10.1038/nnano.2007.418).

Many drugs work by triggering aggregation, but …