Background In workers exposed mostly to laboratory animals (LA), symptoms may be due to irritants or allergens. Correct aetiological diagnosis is important for health surveillance.
Objectives This study aims to test whether work-related (WR) allergen-induced symptoms are associated with a cytokine profile distinct from that due to irritants.
Methods In a cross-sectional study (n=114), WR respiratory and/or skin symptoms were assessed through a standardised clinical examination and sensitisation to rat and/or mouse allergen determined by serum immunoglobulin E. Serum cytokine concentrations were measured by multiplex assays. The predefined cytokine profiles ‘sensitiser’ (interleukin (IL)-4, IL-5, IL-13, eotaxin-1) and ‘irritation’ (IL-8, IL-17A, IL-17F, IL-22) were considered positive, when ≥3 concentrations exceeded the 95th percentile of the asymptomatic non-sensitised group. Results were examined by hierarchical clustering analyses (HCA) and multiple linear regression. Explorative analyses were carried out for nine additional cytokines. Exposure to allergens and endotoxin was assessed in a subpopulation.
Results The prevalence of the profile ‘irritation’ was comparable in 28 symptomatic non-sensitised workers and 71 asymptomatic non-sensitised workers. HCA showed that nearly all symptomatic non-sensitised workers were gathered in two subclusters, characterised by high IL-17A levels, but different IL-8 levels. Multiple linear regression identified drug consumption and current complaints as confounders. Sensitised subjects were too few (n=14) for testing the profile ‘sensitiser’.
Conclusions In this unselected population of LA workers, the profile ‘irritation’ did not prove to be a valuable health surveillance tool. Low power precluded assessment of the profile ‘sensitiser’. The increased IL-17A concentration may originate from irritative constituents of organic dust.
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Contributors Contributions made by each author: AO, FH, PH and PSG devised the conceptual framework of the study. AO, FB, FH, MM, ML, PSG, PH and HD contributed to the realisation of the study. PH, JB and ML did the data analysis. All investigators contributed to the interpretation of the data and to the writing of the paper. Planning, conducting and statistically analysing the study was exclusively the work of the authors. All authors had full access to all the data in the study and had final responsibility for the decision to submit for publication.
Funding The study was entirely funded by the units performing the study.
Competing interests None declared.
Patient consent The study purpose was explained at information meetings, workers received written information and all subjects gave written informed consent.
Ethics approval All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Research involving human participants: The study was conducted in the framework of an analysis of occupational risks of workers exposed to animals. It was conducted according to the Declaration of Helsinki and approved by the Ethics Commission (Kantonale Ethik-Kommission Zürich (KEK), reference number KEK-ZH-Nr. 2012-0142, Zurich (Switzerland), approval dated 15 June 2012).
Provenance and peer review Not commissioned; externally peer reviewed.
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