Datura stramonium agglutinin released histamine from rat peritoneal mast cells that was inhibited by pertussis toxin, haptenic sugar and N-acetylglucosamine-specific lectins: involvement of glycoproteins with N-acetylglucosamine residues.

The N-acetyl glucosamine (GlcNAc)-specific lectin Datura stramonium agglutinin (DSA) rapidly and sugar-specifically released histamine from rat peritoneal mast cells, and pertussis toxin (IAP) inhibited it, suggesting that DSA activated mast cells via an IAP-sensitive G protein pathway. The additive effects of DSA and basic secretagogues such as compound 48/80 that activate IAP-sensitive G protein directly suggest that they shared the same mechanism of action including involvement of the IAP-sensitive G protein. Using lectin-blotting, blots of the corresponding glycoproteins detected by DSA diminished by haptenic sugar or pretreatment of the cells with N-glycosidase F, suggesting that the binding of DSA was responsible for the mast cell activation. The other GlcNAc-specific lectins such as Phytolacca americana mitogen, Solanum tuberosum agglutinin and wheat germ agglutinin (WGA) inhibited the histamine release induced by DSA, suggesting that these lectins were antagonists, but DSA was an agonist. Sialic acid-specific Macckia amurensis mitogen (MAM) inhibited the histamine release, and neuraminidase-treatment decreased mast cell activation induced by DSA. At least four mast cell glycoproteins that have affinity to DSA, WGA and MAM and are sensitive to neuraminidase-treatment were detected by lectin-blotting. Some of them may be binding sites coupled to histamine release including the IAP-sensitive G protein pathway. DSA is a useful tool for studying signal transduction of mast cells including the involvement of the IAP-sensitive G protein.