Mast Cell Degranulation: FcεRI Cross-Linking (2D)

This 2D simulator renders the same closed-form receptor binding kinetics as the 3D mast cell model, projected from a real internal 3D coordinate space so the membrane view can still be dragged to orbit it. Free-floating allergen molecules drift, bind, and bridge IgE-loaded FcεRI receptors; a single binding event does nothing, but once a multivalent allergen physically cross-links two IgE-occupied receptors the pair lights up red, and a live strip chart tracks the resulting cross-link density ρ against a Hill-function threshold in real time. Cross the threshold and the cell fires, releasing a visible burst of histamine-carrying granules before resetting to rest. Tune the allergen dose, receptor density, and degranulation threshold to explore why intermediate allergen doses can trigger a stronger reaction than an overwhelming one (the prozone / high-dose hook effect), and fire a pulse to simulate a real sting or exposure event.