Loading video... VIDEO: These videos show a white blood cell creating a protrusion to reach out to a foreign body. view more Credit: Julien Husson, LadHyX, CNRS, École Polytechnique, Institut Polytec Like a well-trained soldier, a white blood cell uses specialized abilities to identify and ultimately destroy dangerous intruders, including creating a protrusion to effectively reach out, lock-on, probe, and possibly attack its prey. Researchers reporting March 16 in Biophysical Journal show in detail that these cells take seconds to morph into these highly rigid and viscous defensive units. Senior author Julien Husson (@_julienhusson), a biophysicist at École Polytechnique near Paris, and collaborators showed previously that certain white blood cells, called T cells, can push and pull perceived threats via specialized connections. To exert such forces, a cell must reorganize its internal structure, making itself more rigid. In the current study, Husson's team devised a micropipette rheometer to measure the rigidity, along with the viscosity, of a white blood cell during its transformation. The researchers' goal was to quantify the physical changes that arise in a white blood cell as it pushes or pulls on a foreign body--in this case, a bead coated with chemicals to attract the cell.