Role of the polysaccharide and of the lipopolysaccharide in the immunoprotective capacity of Klebsiella pneumoniae ribosomes.

Ribosomes, ribosomal RNA (r-RNA), capsular polysaccharide (PS-K) and lipopolysaccharide (LPS) were isolated and purified from Klebsiella pneumoniae, type I. The protective capacity of these different fractions was investigated in function of their analytical composition. The results show that ribosomes, and in particular, ribosomal RNA have the greatest protective activity at the lowest concentrations. The role of PS-K in the specific immune response to ribosomes was also investigated. Even at very high levels PS-K failed to afford any significant protection. LPS gave no protection. A stable r-RNA/PS-K complex was isolated by means of affinity chromatography. This complex was uncontaminated by LPS and its existence indicated strong bonding between surface polysaccharide antigens and r-RNA. The r-RNA/PS-K complex was not antigenic in itself but conferred good protection when combined with an adjuvant.