PHOSPHOLIPID DISTRIBUTION PATTERN IN UNINDUCED (RESIDENT) AND CASEIN-INDUCED MOUSE PERITONEAL CELLS

Abstract

Mice [230] (ddY, male, 18 g) were divided into 4 groups of 80, 50, 50 and 50. The animals of the last 2 groups were vaccinated i.v. each with 1 mg of BCG. Two weeks later when they were around 30 g in body weight, the mice of both the normal and vaccinated gruops were injected i.p. each with 2 ml of a 6% solution of Hammersten casein. Three days later, cells were collected from the washings of the peritoneal cavities of these stimulated and unstimulated mice. Cardiolipin, phosphatidylethanolamine, phosphatidylcholine, sphingomyelin and lysophosphatidylcholine were the main phospholipids, and the per cent distribution of each phospholipid was calculated regarding the sum of these 5 phospholipids as 100. The stimulation effect of i.p. injection of casein was revealed by 3-5 times as much yield as that from the unstimulated animals. The total lipid content did not increase at all by the stimulation, but rather decreased. This was particularly true concerning phospholipids. This event was apparently due mainly to the decreased amount of phosphatidylcholine and phosphatidylethanolamine, with the exception of cardiolipin. This result is rather contradictory to the general notion that synthesis of phospholipids is enhanced during phagocytosis to perform increased membrane formation. A tentative hypothesis is that lysis and renewal of cellular membranes are taking place in casein-induced macrophages accompanying the most active turnover of phosphatidylcholine and phosphatidylethanolamine.