IgE-mediated 14C-serotonin release from passively sensitized rat mast cells: comparative kinetic study with formaldehyde and ice-cold methods.

The kinetics of IgE-mediated release of serotonin from passively sensitized rat mast cells in vitro was studied by stopping 14C-serotonin release with the application of formaldehyde fixative or ice-cold mast cell medium (MCM). Antigen dose-release curves of 14C-serotonin and/or histamine were comparable when mediator release was terminated with either formaldehyde at a final concentration of 1% or ice-cold MCM 15 min after antigen challenge. However, the kinetic study of immunological mediator release stopped by formaldehyde showed that the addition of antigen resulted in a progressive increase of released 14C-serotonin for 7 min, the release curve being sigmoidal, whereas the application of ice-cold MCM artificially enhanced 14C-serotonin and histamine release in the first 2 min. The results suggest that stopping IgE-mediated release of 14C-serotonin with formaldehyde is a simple, rapid and accurate method of studying the kinetics of mediator release from mast cells.