Effect of disodium cromoglycate on phospholipase a activity: Studies with egg yolk and isolated mast cell systems

The proposal that phospholipase A may be involved in the non-immuno-logical release of histamine from mast cells has been investigated using disodium cromoglycate and simple models consisting of egg yolk emulsions or isolated mast cell systems. The results appear to exclude a role for phospholipase A in histamine release from mast cells. Disodium cromoglycate at concentrations between 10 −7and 10 −3M did not appear to effect the activity of purified snake venom phospholipase A in the egg yolk emulsion substrate system. The enzyme was completely inhibited in the same system by 5 × 10 −4 M EDTA. Purified snake venom phospholipase A alone did not cause significant release of histamine from isolated rat peritoneal mast cells. Although phospholipase A and chymotrypsin acted synergistically to release histamine from mast cells, disodium cromoglycate (10 −6−10 −3M) did not significantly effect this process. In addition, lysis of mast cells by lysolecithin was not inhibited by 10 −6−10 −3M disodium cromoglycate.