BINDING AND GERMINATION OF ASPERGILLUS-FUMIGATUS CONIDIA ON CULTURED A549 PNEUMOCYTES

Invasive pulmonary aspergillosis is acquired through inhalation of con idia. Little is known about early interactions between Aspergillus fum igatus conidia and alveolar epithelial cells, so an in vitro model nas developed to study binding between conidia and A549 cells, a line of type II pneumocytes. Conidia rapidly became attached to confluent mono layers of A549 cells in serum-free medium, reaching a plateau within 4 0 min. Scanning electron microscopy (EM) showed a random pattern of ea rly adherence; viable conidia subsequently became clustered on pneumoc yte surfaces. Following germination of pneumocyte-adherent conidia for 12 h, direct penetration of epithelial cells by hyphae could be demon strated by scanning and transmission EM. These data suggest that an ea rly event following inhalation of A. fumigatus conidia may be binding of conidia to pneumocytes, followed by hyphal penetration of the epith elial cell layer.