The effect of Listeria monocytogenes lipids on the activity of nonspecific immune mechanisms.

The administration of Listeria monocytogenes lipids (LML) in mice resulted in the development of population of macrophages with increased phagocytic and microbicidal activity, as well as higher content of the lysosomal acid hydrolases. The elevation of the serum level of lysozyme, complement and properdin in guinea pigs after LML injection was observed. The normal macrophages cultured in vitro were also activated by LML independently on the presence or absence of autologous lymphocyte. It is concluded that the mechanism of the increase of the host resistance evoked by LML depends on the direct stimulatory effect of LML on the activity of the mononuclear phagocyte system.