Label-free, real-time monitoring of IgE-mediated mast cell activation on microelectronic cell sensor arrays

Immunoglobulin E (IgE)-mediated mast cell activation is involved in the immediate phase of allergic reactions and plays a central role in the onslaught and persistence of allergic diseases. IgE-mediated mast cell activation includes two important events: cell sensitization resulting from IgE binding to Fc (FcepsilonRI) receptor and cell activation triggered by allergen-mediated oligomerization of membrane-bound IgE. Real-time monitoring of these events is needed to dissect the molecular mechanisms underlying IgE-mediated mast cell activation. Existing technologies are limited to label-based end-point assay formats, which detect either early signaling or final phase of mast cell activation. We describe a microelectronic cell sensor-based technology allowing dynamic monitoring of IgE-mediated mast cell sensitization and activation in real-time without any labeling steps. RBL-2H3 mast cells were cultured onto the surface of microelectronic cell sensor arrays integrated into the bottom of microtiter plates, which record electric properties, such as impedance between cell membrane and sensor surface. In the presence of the allergen, dinitrophenyl (DNP)-bovine serum albumin (BSA), anti-DNP IgE-sensitized cells were activated within 5 min and the entire activation process was quantitatively and continuously recorded. Impedance measurements correlate with morphological dynamics and mediator release as measured by beta-hexosaminidase activity, and can be blocked by pharmacological agents, inhibiting IgE-mediated signaling. The assay on microelectronic cell sensor arrays can be scaled up for high-throughput screening of pharmacological inhibitors of IgE-mediated mast cell activation and other cell-based receptor-ligand assays.