Carbohydrate profiling of fungal cell wall surface glycoconjugates of Aspergillus species in brain and lung tissues using lectin histochemistry

The aim of this study was to evaluate, through lectin histochemistry, the expression of N-acetyl-D-glucosamine, L-fucose, D-galactose and glucose/mannose on the cell wall surfaces of Aspergillus species in histopathological specimens of brain (n = 1) and lung (n = 6) tissues obtained during autopsy of patients diagnosed postmortem as having had invasive aspergillosis. Concanavalin A (Con A), wheat germ agglutinin (WGA), Ulex europeus agglutinin I (UEA-I) and peanut agglutinin (PNA), all conjugated with horseradish peroxidase, were employed. Lectin-binding was visualized using 3,3-diaminobendizine (DAB) and hydrogen peroxide in phosphate buffer solution (PBS). We observed expression of N-acetyl-D-glucosamine and methyl-α-D-mannoside on the cell wall surfaces of all evaluated Aspergillus species, while the expression of L-fucose and D-galactose demonstrated inter and intra-specific variations. The results obtained from this study indicate that the use of WGA and Con A lectins permits visualization of Aspergillus structures such as hyphae, conidial heads and conidia in histopathological specimens of brain and lung tissues.