Measurement of macrophage adherence and spreading with weak electric fields

A new method to monitor macrophage attachment on protein-coated surfaces and spreading in response to activating agents is described. Murine macrophages were cultured on small gold electrodes coated with protein, and attachment and spreading were detected as electrical impedance changes. The rate of attachment of cells to fibronectin-coated electrodes was measured to be significantly greater than to other proteins tested. Activation agents used included interferon-gamma, lipopolysaccharide and heat killed Listeria monocytogenes. Addition of each agent to macrophages on electrodes resulted in characteristic patterns in the impedance time course with impedance changes as large as 40%.