Fluorescence microscopical visualization of rat mast cells by means of fluoresceine isothiocyanate labeled protamine sulfate.

Using fluoresceine isothiocyanate labeled protamine sulfate it is possible to stain rat mast cell fractions of isolated periotoneal cells in a selective way. The cells are not degranulated, though they have lost their histamine completely. The method shows the dissociation of the mediator release and the extrusion of the granules.