Phospholipase A2-induced antimycobacterial activity in the membrane fraction obtained from peritoneal exudate cells of guinea pigs.

Tubercle bacilli were preincubated with the membrane fraction separated from casein-induced peritoneal exudate cells of guinea pigs, and subsequently exposed to exogenous phospholipase A2. Marked reduction in viable counts occurred in the incubation mixture at pH 5.6. The additional presence of cholesterol esterase, which alone was inactive, enhanced greatly the phospholipase A2-induced mycobactericidal activity of the fraction. Lipid analysis revealed degradation of phospholipids. The use of cell sap, in place of the membrane fraction, was not only ineffective in the same experimental system, but also neutralized the enzyme-induced activity of the latter. Bacteriostatic effect was also demonstrated in the enzyme-containing Kirchner semi-solid agar medium into which the bacilli were inoculated after being preincubated with the membrane fraction. An additional observation was that the mycobactericidal effect was also revealed when the artificial biomembrane (liposomes) prepared with phospholipids extracted from the exudate cells was used in place of the membrane fraction. These results support such an assumption that toxic fatty acids released from membrane phospholipids have an opportunity to kill the mycobacteria which are in close contact with the membrane.