Quantification of obeche wood allergen: Development of a sensitive sandwich-ELISA for occupational exposure...

Obeche wood is a prominent cause of allergic occupational asthma. To reduce the risk of immunoglobulin E (IgE)-mediated sensitization it is important to assess airborne obeche wood allergen concentrations at exposed workplaces. Therefore, a highly sensitive obeche wood allergen immunoassay was developed and applicability was proven on airborne passive dust samples in Spanish wood workshops. Obeche wood sandwich enzyme-linked immunosorbent assay (ELISA) polyclonal antibodies (pAbs) were developed. Test specificity was verified by different wood and mold extracts. Obeche wood allergen monitoring was conducted in four Spanish wood workshops, including wood-dust-exposed and nonexposed areas inside and outside the workplaces, as well as controls. Dust was collected with electrostatic dust collectors (EDC). Measuring range of the obeche wood sandwich-ELISA was between 36 pg/ml and 1.6 µg/ml. The test system showed only marginal reactivity to other hardwoods and no reactivity to softwoods and molds. Obeche allergen was detected in all EDC from workplaces. The highest concentration was measured in the workshop with the longest obeche wood exposure (geometric mean [GM]: 7548 µg/m²); shorter obeche wood processing periods resulted in lower amounts of allergen (GM: 29 µg/m²). Obeche wood allergen transfer from exposed workplaces to nonexposed areas inside and outside the workshop was assessed. In control EDC from nonexposed facilities/homes no obeche wood allergen was found. The new obeche wood sandwich-ELISA is a valid tool to quantify obeche allergen exposure. Evidence indicates it will be possible to monitor obeche allergen exposure during different processes, as well as transfer effects in nonexposed areas.