NON‐IMMUNOLOGICAL RELEASE OF SLOW‐REACTING SUBSTANCE FROM GUINEA‐PIG LUNGS

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Abstract
During incubation with calcium ionophore A23187, sensitized and unsensitized guinea‐pig chopped lung released a slow‐reacting substance (SRS) and histamine. SRS possessed many characteristics of slow‐reacting substance of anaphylaxis (SRS‐A). It was inactivated by arylsulphatase, antagonized by FPL55712 (1 μg/ml) and more stable in alkali than acid. Furthermore, it behaved like SRS‐A by stimulating arachidonic acid metabolism in guinea‐pig isolated perfused lungs. Maximal ionophore generation of SRS in sensitized lung was greater than maximal anaphylactic generation of SRS‐A but the release of histamine was not significantly different. Simultaneous challenge with antigen and ionophore produced more SRS‐like or SRS‐A‐like activity than either stimulus alone. These results have shown a non‐immunological release from guinea‐pig lung of SRS which was similar (or possibly identical) to SRS‐A. It is suggested that in addition to mast cells, other cell types may be involved.