Characteristics of histamine secretion from rat peritoneal mast cells sensitized to the nematode Nippostrongylus brasiliensis.

Peritoneal mast cells from rats immunized with the nematode Nippostrongylus brasiliensis released histamine on challenge with antigen in both the presence and absence of added calcium. The response under the latter conditions was abolished by depletion of sequestered stores of the cation and probably reflected mobilization of these stores. The release was potentiated by brief pretreatment with chelating agents and inhibited (in the absence of phosphatidyl serine, PS) by supramaximal concentrations of calcium. Calcium bound to superficial sites in the membrane may then regulate the secretory process. Histamine release in both the presence and absence of calcium was enhanced by adenosine. Only the former response was potentiated by PS, in keeping with the view that the lipid promotes influx of the cation from the extracellular environment. The activated state induced by antigen decayed with time but PS slowed this process. Histamine secretion in the absence of calcium was more rapid than in the presence of the cation, consistent with the release of bound calcium in a pulse of short duration.