Antigenic Activity of Polysaccharides of B. rhinoscleromatis.

Abstract

Polysaccharide obtained from B. rhinoscleromatis through extraction of dried bacterial cells in weak acetic acid solution provokes in immunized rabbits the formation of complement-fixing antibodies and induces in guinea pigs active sensitization. In this experiment an attempt was made to demonstrate that the antigenicity of the polysaccharide of this bacterial species is analogous to that of the whole bacterial cell. It seemed also of interest to compare the immunological properties of this polysaccharide with that prepared by the method in which the treatment of the bacteria by heat was avoided.

A stock culture of B. rhinoscleromatis was passed through mice 3 times until its agar culture acquired markedly slimy appearance. The first type of polysaccharide was prepared in accordance with the method previously reported. 1 The second type of polysaccharide was obtained from the same microörganism by spontaneous autolysis of bacterial suspension in distilled water. Polysaccharides prepared in this manner showed none of the usual protein reaction, the amount of nitrogen in both types of substance being equal to 0.24%. Immunological reactivity of the polysaccharides was determined by testing them against immune rabbit serum prepared by immunization of these animals with formol killed culture of B. rhinoscleromatis. It was found that both substances reacted equally well giving positive precipitation and complement-fixation tests in concentration of 1:6,000,000 and 1:64,000,000 respectively. Cross absorption tests showed that the polysaccharide prepared by autolysis of bacterial bodies removed from anti-bacterial serum all precipitin, whereas, the serum absorbed with the polysaccharide prepared by extraction with acetic acid still gave precipitin reaction to the titer of 1:500,000 when tested against the former type of substance. This indicated that the polysaccharide obtained by autolysis is more complex than that obtained by acid extraction.