Background: Evidence is accumulating that the alveolar collectin surfactant protein A (SP-A) plays an important role in the first line of defence against infiltrating pathogenic micro-organisms and viruses. The ability of SP-A to facilitate the binding and uptake of Cryptococcus neoformans by monocytes, polymorphonuclear leucocytes, monocyte-derived macrophages, and rat and human alveolar macrophages was investigated. Materials and Methods: Binding, inhibition, and phagocytosis experiments were performed using a flow cytometry technique. Results: SP-A bound to the acapsular C. neoformans in a concentration-dependent manner. This binding was partly calcium dependent and could be inhibited by mannose (ID 50=3 mM) and glucose (ID 50=2.1 mM), but not by galactose (ID 50= 391 mM). SP-A displayed a better binding to Aspergillus fumigatus conidia than to C. neoformans. This binding was strongly calcium dependent. SP-A did not function as an opsonin for any of the phagocytes studied. Conclusion: Our results indicate that the observed difference in the ability of SP-A to promote binding of C. neoformans or A. fumigatus might reflect a different way SP-A binds to C. neoformans.
Full conference title:
38th Interscience Conference on Antimicrobial Agents and Chemotherapy
- ICAAC 38th