Structural requirements for arthritogenicity of peptidoglycans from Staphylococcus aureus and Lactobacillus plant arum and analogous synthetic compounds.

The comparative studies on the arthritogenicity of chemically well defined peptidoglycans (PG)2 from the cell walls of Staphylococcus aureus (FDA 209P) and Lactobacillus plantarum (ATCC 8014) showed that 1) a polymer of disaccharide-peptide with or without the presence of N-acetylglucosaminyl-ribitol-teichoic acid produced severe arthritis; 2) oligosaccharide-peptides with or without the special structure (N-acetylglucosaminyl-ribitol-teichoic acid in S. aureus, a polymer of rhamnose and glucose in L. plantarum) produced severe disease; 3) disaccharide-heptapeptide-disaccharide with or without the presence of either glucose-ribitol-teichoic acid or a polymer of rhamnose and glucose appeared to be arthritogenic but much less effective for disease production; 4) N-acetylmuramyl-heptapeptide-N-acetylmuramic acid and disaccharide-hexapeptide were non-arthritogenic; 5) none of the synthetic N-acetylmuramyl-peptides, including tetrapeptide, produced the disease. Thus it is concluded that arthritis-inducing activity is related to the peptidoglycan moiety but not to the special structure, and the most important moiety responsible for disease production may be located in a chain length of two or more disaccharide units on PG subunits. However, it is discussed that non-arthritogenicity of peptidoglycans, including synthetic compounds, may be due to a lack of adjuvanticity in rats rather than a lack of antigenic determinant(s) responsible for production of arthritis.