A new assay for the measurement of mediator release from rat peritoneal mast cells.

In this report, we describe a new in vitro experimental system for monitoring the release, and inhibition of release, of [3H]-serotonin from rat peritoneal mast cells, which can be used as a novel screen for evaluation of compounds effective in immediate hypersensitivity reactions. This assay is an improvement on existing assays since the cells are not required to be exposed to hormones at any time during the procedure. In this assay, 1 microgram/ml of compound 48/80 consistently produced a 6- to 8-fold-increase in release of serotonin with a low background release of 4-5%. Disodium chromoglycate (DSCG), a standard inhibitor of histamine release, effectively inhibited compound-48/80-stimulated serotonin release with an average I50 of 2.1 X 10(-4) M. Several other potential antiasthmatic agents were far more potent than DSCG.