Histamine release from rat mast cells induced by protamine sulfate and polyethylene imine

The protamine sulfate-induced release of histamine from mast cells in a non-cytotoxic reaction, similar to the 48/80-induced secretion. Polyethylene imine was found to be a less potent releaser. It is a cytotoxic substance without specificity for mast cells and acts on membranes generally. Although the two agents are related concerning their molecular weight and polybasicity, their mode of action on mast cells is clearly different.