Isolation of an acidic polysaccharide antigen from Propionibacterium acnes

An acidic polysaccharide antigen is released from Propionibacterium acnes I and II during growth. The molecular weight of the antigen was heterogeneous and when fractionated on a Sepharose CL-6B column, the antigen was detected at Kav values of between 0.1 and 1.0. The pI of the antigen was below 3.5. Rabbit antiserum raised against purified acidic-polysaccharide agglutinated P. acnes showing that the polysaccharide was a surface antigen. Human antibodies towards whole P. acnes-II organisms were quantitated by an agglutination technique, and antibodies towards purified acidic polysaccharide were quantitated by single radial immunodiffusion. A high prevalence of antibodies against whole bacteria and the acidic polysaccharide was found in sera from healthy individuals. The antibody titre in sera from acne patients was significantly higher than that in sera from blood donors.