Measurement of anti-allergic effects using flow-through piezoelectric biosensors based on the mast cells exocytosis

IgE-mediated degranulation of mast cells is involved in many allergic diseases due to the proallergic and proinflammatory substances released from granules when they become activated. The initial step of sensitization requires IgE antibodies to bind to high affinity FcεRI receptors. The following activation of cells becomes triggered by multivalent antigen-induced oligomerization of the IgE/FcεRI complexes. The activation reaction is accompanied by microstructural changes of the cells, which can serve as signal-generating event. To monitor such events in real time, a piezoelectric (PZ) quartz crystal resonator sensor was adopted to provide semi-quantitative and qualitative information relating to the structural changes and dynamics of the process. The sensitized RBL-2H3 mast cells were cultured on poly-L-lysine coated gold surface of quartz crystal integrated in the flow cell and connected with the detector providing resonance frequency and resistance of the piezosensor. The activation of mast cells by antigen–dinitrophenyl conjugated to bovine serum albumin, was continuously monitored for several hours. Furthermore, quercetin, as the efficient inhibitor of the degranulation process, was tested in micromolar concentrations. The observed PZ response was confirmed using atomic force microscopy for imaging topography and morphological changes of the mast cells fixed at different stages of the degranulation. The results from the constructed PZ biosensor proved to be sensitive, fast, and label-free tool for screening of anti-allergic drugs.