CORRELATION OF ADJUVANT ACTIVITY AND CHEMICAL STRUCTURE OF WAX D FRACTIONS OF MYCOBACTERIA

Abstract

By fractionation of wax D from mycobacteria by ultracentrifugation in ether, it is possible to prepare from wax D of human strains peptide-containing and non-peptide-containing compounds. The peptide-containing fractions, like the parent wax D, were able to act as adjuvants by increasing serum anti-ovalbumin levels, by increasing corneal hypersensitivity to ovalbumin, and by inducing encephalomyelitis after homologous guinea-pig brain injection. The peptide—carbohydrate moiety resulting from hydrolysis of the whole wax D was found inactive in all these biological effects.

When the same centrifugal technique was applied to several bovine types of Mycobacterium tuberculosis, M. avium and to atypical and saprophytic mycobacteria, analogous peptide and non-peptide-containing fractions were obtained. The amino acid patterns of these were of great variety, and in most cases differed from those present in human type wax D. In three instances a small proportion of a peptide-containing fraction was obtained (from M. phlei, M. avium and an atypical mycobacterium), which closely resembled a human type wax D. These fractions were found to have adjuvant activity. All other fractions of wax D of bovine, avian and saprophytic strains were inactive.

These facts support the role of a peptide of D- and L-alanine, D-glutamic acid and meso-α,α'-diaminopimelic acid in determining the adjuvant action of wax D fractions and whole mycobacteria. The structure of the peptidoglycolipid of an adjuvant-active mycobacterial wax corresponds closely in amino acid, amino sugar and hexose composition with the mucopeptide of the bacterial cell wall, and evidence is discussed for the concept of wax D fractions as partial replicas of a fundamental cell wall polymer.