Some biological properties of an endotoxic lipopolysaccharide from the typhus group rickettsiae

A lipophilic thermostable lipopolysaccharide (LPS) complex was isolated by phenol extraction from purified suspensions of the typhus group rickettsiae. The LPS complex is antigenic and possesses some endotoxic properties such as toxicity for actinomycin D-treated mice, pyrogenicity for rabbits and guinea pigs, ability to elicit hypothermia in white rats and local Schwartzman reaction and active cutaneous anaphylaxis in rabbits.