Discussion Aspergillus fumigatus is known as the most common cause of IA in humans. The extracellular proteins of A. fumigatus, which functions in enabling the fungi to adhere to host tissues and take up nutrients

from the hosts, play an important role in the LDK378 supplier interaction between fungi and hosts. The extracellular location of these proteins enables the proteins to interact easily with the host immune system. Accordingly, studies on the immunogenic nature of these extracellular proteins are of particular importance to understand the pathogenesis of A. fumigatus. The immunogenic proteins may represent candidate markers for the diagnosis of IA. In fact, preparations of A. fumigatus extracellular proteins have been used to detect antibodies in the sera of human patients or experimentally infected animals, and culture filtrates have also been used to raise polyclonal antibodies to detect A. fumigatus antigens in the sera or urine of patients or experimentally infected rats [26, 27]. Our group has previously observed that high

titers of antibodies against extracellular proteins of A. fumigatus are often present in the sera of critically ill IA patients (unpublished data). However, knowledge of the extracellular proteins of A. fumigatus and the corresponding antibodies is limited. To investigate the immunodominant antigens, the extracellular proteins at different intervals were extracted from 4 media (Aspergillus minimal medium, YEPG, Czapek-Dox medium, and RPMI-1640), then probed Selumetinib molecular weight with sera of IA patients. The results indicated that the protein yield

reached a maximum at 14 days, and the YEPG culture supernatant Enzalutamide contained the maximum number of proteins reacting with the sera in comparison to other media (unpublished data). Thus, the 14-day YEPG filtrate proteins were used in a subsequent study. In the present study, the immunodominant proteins from the culture filtrate of A. fumigatus were detected using an immunoproteomic approach. The immunoreactive protein spots showing a significantly different pattern of recognition in sera from IA patients when compared with specimens from controls were characterized by MS. Of 17 identified proteins, 7 have been reported as antigens of Aspergillus and/or other fungi. For example, DppV, TR, FAD-dependant oxygenase, pectate lyase A, aspartyl aminopeptidase, and NAD-dependent malate dehydrogenase are already known as antigens or allergens of Aspergillus [28–31]. Fructose-bisphosphate aldolase was identified as an immunogen in patients with systemic candidiasis [32]. Furthermore, diverse groups have reported that some metabolic enzymes interact specifically with human extracellar matrix proteins, such as fibronectin, laminin, and integrin-like vitronectin [33, 34], and are involved in adhesion and pathogenesis.