Abstract
BackgroundObeche wood dust is a known cause of occupational asthma where an IgE-mediated mechanism has been demonstrated.ObjectiveTo characterize the allergenic profile of obeche wood dust and evaluate the reactivity of the proteins by in vitro, ex vivo and in vivo assays in carpenters with confirmed rhinitis and/or asthmaMaterials and methodsAn in-house obeche extract was obtained, and two IgE binding bands were purified (24 and 12 kDa) and sequenced by N-terminal identity. Specific IgE and IgG, basophil activation tests and skin prick tests (SPTs) were performed with whole extract and purified proteins. CCD binding was analyzed by ELISA inhibition studies.ResultsSixty-two subjects participated: 12 with confirmed occupational asthma/rhinitis (ORA+), 40 asymptomatic exposed (ORA−), and 10 controls. Of the confirmed subjects, 83% had a positive SPT to obeche. There was a 100% recognition by ELISA in symptomatic subjects vs. 30% and 10% in asymptomatic exposed subjects and controls respectively (p<0.05). Two new proteins were purified, a 24 kDa protein identified as a putative thaumatin-like protein and a 12 kDa gamma-expansin. Both showed allergenic activity in vitro, with the putative thaumatin being the most active, with 92% recognition by ELISA and 100% by basophil activation test in ORA+ subjects. Cross-reactivity due to CCD was ruled out in 82% of cases.ConclusionsTwo proteins of obeche wood were identified and were recognized by a high percentage of symptomatic subjects and by a small proportion of asymptomatic exposed subjects. Further studies are required to evaluate cross reactivity with other plant allergens.
Highlights
Wood is a known sensitizer widely extended in the construction and furniture industries worldwide [1,2]
83% had a positive skin prick tests (SPTs) to obeche
We evaluated the reactivity of the potentially allergenic proteins by in vitro, ex vivo and in vivo assays in a well-characterized population of carpenters with confirmed rhinitis and/or asthma due to obeche wood exposure and two control populations
Summary
Wood is a known sensitizer widely extended in the construction and furniture industries worldwide [1,2]. A high molecular weight class I chitinase was described (Trip s1), and still remains the only allergen identified so far [10] This 38 kDa protein shares a high molecular similarity with Prs a 1 (avocado allergen) and with Hev b 6, and cross reactivity has been demonstrated in a small group of sensitized subjects [10,12]. This allergen was not recognized by most subjects in the aforementioned studies [6,9,11], so its relevance in other populations remains unknown. Obeche wood dust is a known cause of occupational asthma where an IgE-mediated mechanism has been demonstrated
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