Real-time analysis of ligand-induced cell surface and intracellular reactions of living mast cells using a surface plasmon resonance-based biosensor.

Surface plasmon resonance (SPR)-based sensors have been used to detect the binding between interactive molecules. We applied the SPR technology to the analysis of interactions between living cells and molecules reactive to the cells, using mast cells and mast cell-reactive antigens. The exposure of dinitrophenol-human serum albumin (DNP-HSA), an antigen that stimulates mast cells, to IgE-sensitized mast cells induced a robust and long-lasting SPR signal in a dose-dependent manner. The maximal increase in SPR signal induced by 100 ng/ml DNP-HSA was 0.200 +/- 0.120 angle (mean +/- SD, n = 37), about 1000 times larger than the theoretically expected increase for the simple binding of DNP-HSA to Fc(epsilon)RI, the high-affinity IgE receptor. A small, but similarly prolonged signal was observed when the cells were stimulated by an agonist of the adenosine A3 receptor. The signal induced by DNP-HSA was abolished by genistein, and partially inhibited by phorbol 12-myristate 13-acetate and wortmannin. Interestingly, the signal induced by DNP-HSA was only weakly inhibited by DNP-lysine, suggesting that DNP-lysine manifests its action not by inhibiting, but by modulating the crosslinking of Fc(epsilon)RI. We concluded that SPR sensors can detect biologically significant signals in a real-time manner from the interactions between cells and molecules reactive to the cells.