UCSF

The capacity to extract slow-reacting substance of anaphylaxis (SRS-A) from human lung tissue or cells after immunologic activation, together with the measurement of SRS-A in both the extract and the surrounding fluid, permits study of total SRS-A generation. That the material extracted is SRS-A was established by both differential bioassay and purification. SRS-A accumulation was entirely intracellular after limited IgE-dependent direct or reversed anaphylactic activation. Intracellular accumulation also generally preceded release, with generation of SRS-A continuing well beyond a plateau in the cellular SRS-A level and the release of preformed mediators. The quantity of SRS-A generated after immunologic activation was modulated by the introduction of exogenous cyclic nucleotides, revealing a site of cyclic nucleotide action distinct from that on mediator release. The capacity to determine not only the release of preformed mediators but also the generation of a newly formed mediator, the sum of SRS-A in cells and supernate, adds an additional dimension to the analysis of the cellular events of immediate hypersensitivity.