Effect of a lysolecithin analogue on nonspecific resistance to infection of mice

The effect of racemic 1-octadecyl-2-methoxy-sn-glycero-3 phosphorylcholine (ET-18-OCH3) on the nonspecific resistance of mice to infection with Salmonella typhimurium was investigated. Two S. typhimurium strains with different virulence were studied and no effect was observed in either case at concentrations of ET-18-OCH3 up to 100 micrograms/mouse. However, a concentration of 500 micrograms/mouse caused decreased resistance to S. typhimurium, correlating with a depression of carbon clearance. Treatment of macrophages with ET-18-OCH3 in vitro inhibited phagosome-lysosome fusion, but had no effect on zymosan-induced luminol-dependent chemiluminescence. The relationship between the adjuvant and nonspecific anti-infectious activity of ET-18-OCH3 and other compounds is discussed.