Cigarette smoke and N-acetylcysteine: interference with the bactericidal properties of serum

The bactericidal properties of normal serum are an important feature in host defence; it has been suggested that they are depressed by cigarette smoke. The aim of the present study was to investigate the in vitro depressant effect of cigarette smoke on antibacterial activity of rabbit serum and its interaction with the well-known antioxidant agent, N-acetylcysteine. Escherichia coli was used to study the bactericidal activity of the complement-dependent system and Staphylococcus aureus was used to study the thermostable bactericidal system. It was found that exposure of serum and bacteria to cigarette smoke significantly decreased the bactericidal powder of serum; when N-acetylcysteine was added to the incubation mixture, however, a marked inhibitory effect on the toxic action of smoke on rabbit serum was observed.