Analysis of peptidogalactomannans from the mycelial surface of Aspergillus fumigatus.

Peptidogalactomannans (pGMs) from mycelium of two strains of Aspergillus fumigatus were fractionated by Cetavlon precipitation and size exclusion chromatography and their carbohydrate structures analysed using methylation-fragmentation analysis, partial acetolysis and 13C-nuclear magnetic resonance spectroscopy. The most significant difference between the pGMs of the two strains was the degree of branching and the proportion of non-reducing ends of alpha-D-Manp and beta-D-Galf units. Methylation data showed that the pGM from AF 2109 contained alpha-D-Manp and beta-D-Galf non-reducing end units in a proportion of 3:1 while, in contrast, the proportion of these structures in pGM from AF 2140 was 7:1, resulting in a highly branched structure. The immunoreactivity of the pGM fractions was tested by indirect immunofluorescence. The fractions were also tested in an ELISA system with rabbit antiserum raised to whole cells of A. fumigatus NCPF 2140 and with serum from patients with either proven aspergilloma or ABPA. The carbohydrate moiety of the pGM appears to be responsible for the antigenicity. Periodate treatment, partial acid hydrolysis and beta-elimination removed most of the antibody binding capacity.