Comparison of histamine release induced by synthetic polycations with that by compound 48/80 from rat mast cells.

We compared the histamine release induced by polyethylenimines and polyallylamines with that induced by compound 48/80. Lidocaine inhibited the histamine release induced by polyethylenimine with a molecular weight of 600 (PEI6), but disodium cromoglycate did not. The histamine releases induced by all polyethylenimines and polyallylamines tested were inhibited by lidocaine, but not by disodium cromoglycate. Islet activating protein inhibited the histamine release induced by PEI6. Its effects on the release by other polyethylenimines and polyallylamines were less than that on PEI6. It is likely that the inhibition of G proteins by islet activating protein resulted in a decrease of the histamine release. This possibility was supported by the finding that guanyl-5'-(beta, gamma-imino) triphosphate enhanced the histamine release. An inhibitor of polyphosphoinositide phosphodiesterase, neomycin, did not affect the histamine releases induced by these polymers. The effect of PEI6 seemed to resemble that of compound 48/80. After pretreatment of mast cells with wheat germ agglutinin and with Limax flavus agglutinin, releases of histamine induced by PEI6 and compound 48/80 decreased, suggesting that the binding sites of PEI6 and compound 48/80 had sialic acid and/or N-acetyl glucosamine residues. The binding site for PEI6 seemed to especially overlap those of compound 48/80.