Endotoxic properties of gramnegative bacteria and their susceptibility to the lethal effect of normal serum.

effect of normal serum (Rowley, 1956), (b) an array of normal serum components including specific antibody, complement and lysozyme are required for conversion of Gram-negative bacteria to spheroplasts (Michael and Braun, 1959; Carey et al, 1960), and (c) in the course of the bactericidal action of serum there occurs a striking reduction in the endotoxic and antigenic properties of the bacteria (Landy et al, 1960). In the light of these developments implicating the somatic complexes as at least the primary target for the bactericidal effects of serum, an attempt was made to determine whether marked differences in the bactericidal effectiveness of serum on members of antigenically related bacterial strains are related to the content of endotoxin in these bacteria.