New insights into the role platelets in antifungal host defence

C. Lass-Flörl, S. Unterdorfer, W. Nussbaumer, M.P. Dierich

Author address: 

Innsbruck, AT

Abstract: 

Background: We observed that serotonin (5 HT) acts fungicidal against Aspergillus species and decreases fungal virulence in vitro. In humans, 5 HT is stored in platelets and the 5 HT concentration in granules is about 65 mM. These data and the coincidence of an increased infection rate and low 5 HT levels in certain diseases let us to examine the role of platelets in antifungal host defence. Methods: We investigated the expression of platelets surface receptors (CD 62 P, CD 63 and CD 154) following Aspergillus (hyphae) exposition by fluorescent labelling. Platelets were mixed with fungi (ratio 100:1, 10:1) and incubated for 1 h at 37°C. Platelets activation and adherence on hyphae of Aspergillus sp. was investigated with a Zeiss DSM 950 scanning electron microscope (SEM). The XTT test was applied to assess platelets and platelets/neutrophils effects on viability. The influence on fungal growth was examined by assessing hyphal elongation. Clinical isolates of Aspergillus fumigatus (n = 2) and Aspergillus terreus (n = 2) were used for this study; each test was performed in triplicate and repeated three times. Results: All Aspergillus spp. induced platelet activation as the CD 62P, CD 63 and CD 154 antigens were clearly induced and visualized by fluorescence microscopy; strain dependent expressions were observed. Spread of irregular shaped platelets over hyphal surfaces was shown by SEM. Platelets decreased the ability of hyphae to reduce XTT, co-incubation with polymorphonuclear neutrophils increased fungal damage significantly (p
2006

abstract No: 

P587

Full conference title: 

16th European Congress of Clinical Microbiology and Infectious Diseases
    • ECCMID 16th (2006)