Aspergillus fumigatus is a saprophytic fungus responsible for 90% of aspergillosis in humans. This study focused on the effect of diffusible spore surface component(s) from Aspergillus fumigatus (termed AfD) on the function of human neutrophils. Neutrophils are an important first line of defence and have a short life-span that involves an orchestrated process of migration, phagocytosis and killing. Human neutrophils were treated with AfD and migration was assessed by the ability of neutrophils to change shape (polarise) and transverse a polycarbonate filter. Phagocytosis was measured by the ability of neutrophils to ingest FITC-labeled E. coli and the respiratory burst was measured by the release of superoxide anion. Further investigations looked at AfD-induced programmed cell death (PCD). Results showed AfD to reduce neutrophil polarisation (76±6%), migration (57± 29%), phagocytosis (31±6%) and respiratory burst (95±2%). AfD also induced PCD through a heat-sensitive component(s); therefore, it is likely that the anti-inflammatory properties are explained by the AfD-induced PCD. Furthermore, AfD has heat-sensitive and heat-stable active compounds suggesting multi-component activity.