Potentiation of Anaphylactic Histamine Release from Isolated Rat Pleural Mast Cells by Rat Serum Phospholipids

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Abstract
Isolation of sensitized rat mast cells by density gradient centrifugation in Ficoll decreases the histamine release obtained when they are subsequently exposed to antigen. The histamine release from such isolated cells is potentiated by the addition of 2 % boiled rat serum. This potentiation is dose‐dependent and has a temperature optimum of about 25°C. The potentiating activity was localized to the serum phospholipid fraction. Of the pure phospholipids studied (LPC, PC, PE, PI, PS and SM) only phosphatidylserine and lysophosphatidylcholine were found to potentiate the histamine release. The mechanism behind this potentiation is discussed and it is suggested that the potentiation by phosphatidylserine and lysophosphatidylcholine is due to a requirement of these phospholipids for the ion exchange (Na+, K+and Ca++) or the adenylcyclase activity essential for the histamine release process.