Abstract
Acidic phospholipids neutralized the antistaphylococcal activity of rabbit, human, and rat serum and purified rabbit beta-lysin as well. Several tissue bactericidal factors and cationic antibiotics were also neutralized. The neutralizing ability of all anionic lipids tested, together with the lack of this ability for the electrostatically neutral phosphatidylcholine, suggested that neutralization resulted from formation of electrostatic complexes between negative charges on the lipids and positive charges on the bactericidal substances. The neutralization of these host defense systems by phospholipids can explain the ability of phospholipids to increase bacterial virulence.