Inhibition by disodium cromoglycate of anaphylactic histamine secretion from rat peritoneal mast cells in the presence of phosphatidylserine.

The lipid phosphatidylserine (PS) markedly potentiated anaphylactic histamine secretion from isolated rat peritoneal mast cells in the presence of extracellular calcium ions. The compound correspondingly reduced the inhibitory effect of disodium cromoglycate on the secretion induced by optimal concentrations of antigen. However, at a constant concentration of PS, suboptimal amounts of antigen were effectively inhibited by the drug. The inhibitory power of cromoglycate increased as the concentration of antigen was decreased and the corresponding control release of histamine declined. At control values similar to those observed without addition of PS, the drug inhibited secretion to a similar extent as in the absence of the lipid. At given concentrations of PS and antigen, the potency of the drug increased with decreasing degrees of sensitization of the experimental animals. These effects are not likely to reflect a direct interaction between the drug and PS since increasing the concentration of the lipid by one hundred-fold did not affect the inhibitory effect of the chromone. Further, the latter was essentially equiactive in the presence and absence of PS in calcium-free media, conditions under which the lipid did not enhance histamine release. These results are discussed in terms of the proposed modes of action of PS and cromoglycate.