A Synthetic Acyl Polysaccharide and the Hemagglutination Activity

From Mycobacterium tuberculosis, a serologically specific polysaccharide was purified. It contained mannose, arabinose, and a trace of glucose. It was not active in hemagglutination (HA) reaction. Partial acylation of the polysaccharide was carried out with palmitoylchloride, and the synthetic lipopolysaccharide contained 15.1 per cent of esterified palmitic acid. The synthetic lipopolysaccharide had hemagglutination activity and 0.5 microg was able to sensitize 1 ml of 2 per cent erythrocyte suspension; it had the same activity as the natural antigenic lipopolysaccharide. The same antibody in the antiserum was involved in the hemagglutination reaction with both the synthetic and natural lipopolysaccharides. The sensitizing activity of the synthetic lipopolysaccharide was completely neutralized by cholesterol. Model experiments showed that the lipid moiety of hemagglutination antigen was essential for the sensitization of erythrocytes. The mechanism of the hemagglutination reaction is discussed.