Is in vitro cytokine release a suitable marker to improve the diagnosis of suspected mold-related respiratory symptoms? A proof-of-concept study

Indoor mold infestation can lead to a variety of adverse health effects, including allergic and non-allergic respiratory complaints. Especially if no evidence of an allergic reaction can be found for the complaints, diagnostic tools that might explain mold-associated health problems are missing. As a proof-of-concept, in the present study whole blood assay (WBA) was used to determine cellular response by measuring cytokine release (IL-1β and IL-8) after in vitro stimulation. Blood was available from a total of 48 subjects. By questionnaire, complaints and possible mold exposure were documented. Specific in vitro blood stimulation was tested with Escherichia coli endotoxin and extracts of different molds (Aspergillus fumigatus, Penicillium chrysogenum, Aspergillus versicolor, and Cladosporium herbarum). To characterize the relevance of WBA in describing the mold-induced immune response, we compared the following groups: asthmatics vs. non-asthmatics, mx1-sensitized vs. non-mx1-sensitized, mold-exposed vs. non-mold-exposed. In response to endotoxin stimulation, a significantly higher IL-1β release was found in mx1-sensitized than in non-mx1-sensitized subjects. Furthermore, the blood of asthmatics showed significantly higher IL-8 and IL-1β release after stimulation with Penicillium chrysogenum and endotoxin, respectively, compared to non-asthmatics. However, no significant difference in the level of cytokine release was observed between the mold-exposed and non-exposed group, neither after endotoxin nor mold stimulation. In conclusion, the WBA used in this study is not a suitable tool for clinical routine diagnostic workup. Our data suggests that WBA reflects cellular differences that are disease-related but not directly attributable to mold exposure. However, in combination with further data, WBA will be a helpful und interesting tool in research, e.g., in description of the complex immune response to molds.