Eosinophilia and mast cell hyperplasia induced by parasite phospholipid.

Phospholipid preparations from the nematode Ascaris suum or cysts of Echinococcus granulosus (hydatid cysts) induced an eosinophilia when injected into the peritoneal cavity of rats. Peritoneal eosinophilia persisted throughout 21 days of daily injections of Ascaris lipid and was accompanied by blood eosinophilia, mast cell granule lysis and mast cell hyperplasia. The active material consisted of lecithin and lecithin plasmalogen, and in aqueous suspension had a membrane-like appearance. Electron microscopy revealed that the phospholipid was ingested by all types of cells in the peritoneal cavity, including mast cells, and was rapidly broken down by eosinophils. Phagocytosis was found to be complement dependent. The lipid combined with properdin in human serum and stimulated complement breakdown via the alternative complement pathway.