The effect of phosphatidyl serine on the activation stage of histamine release induced by neutrophil cationic protein.

Histamine release from rat mast cells induced by cationic protein (band 2) from rabbit neutrophil lysosomes occurs in Ca++-deficient medium. At higher concentrations of Ca++ the release is inhibited. Strontium not only supports, but also enhances the release of histamine in the absence of Ca++. Progressive enhancement of release occurs between 1.8 and 14.4 mM Sr++. The release of histamine from mast cells, activated at low temperature (0-4 degrees C) in the presence of 14.4 mM Ca++ and then washed prior to incubation at 37 degrees C, is inhibited. However, if phosphatidyl serine (PS) (10 microgram) is present with 14.4 mM Ca++, the inhibition is reversed. There is also inhibition of release when cells, activated in the presence of 1.8 mM Ca++, are incubated in the second stage with 14.4 mM Ca++, but this inhibition is less pronounced than when the 14.4 mM Ca++ is in the activation stage. PS enhances the release in the presence of both Ca++ and Sr++. The presence of PS in the activation stage enhances the release, but there is no significant enhancement when cells activated in the absence of PS are washed and incubated in the presence of PS. This suggests that PS enhancement of histamine release occurs at the activation stage, probably through the efficient delivery of calcium to the membrane sites, thereby increasing the efficacy of the membrane perturbation by band a protein.