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Title: Class I chitinases, the panallergens responsible for the latex-fruit syndrome, are induced by ethylene treatment and inactivated by heating
Authors: Sánchez-Monge, Rosa
Blanco, Carlos
Díaz Perales, Araceli
Collada, Carmen
Carrillo, Teresa 
Aragoncillo, Cipriano
Salcedo, Gabriel
UNESCO Clasification: 32 Ciencias médicas
320701 Alergias
Keywords: Class I chitinases
Fruit panallergens
Green bean
Latex-fruit syndrome
Ethylene induction, et al
Issue Date: 2000
Journal: Journal of Allergy and Clinical Immunology 
Abstract: Background: Class I chitinases have been identified as the major panallergens in fruits associated with the latex-fruit syndrome, such as avocado, banana, and chestnut. However, other plant foods containing these enzymes have not been related to this syndrome. Objective: We sought out class I chitinases in the green bean, a legume that is known to express chitinases but is not associated with latex allergy, and examined whether the content or allergenic activity of chitinases can be modified by physical or chemical treatments. Methods: IgE-binding proteins in untreated bean samples, as well as in ethylene- and heat-treated samples, were detected by using a pool of sera from patients with latex-fruit allergy. Putative allergens were purified by cation-exchange chromatography and characterized by N-terminal sequencing, enzymatic activity assays, immunodetection with sera and antichitinase antibodies, and immunoblot inhibition tests. Skin prick tests with untreated and heated purified allergens were also carried out. Results: An IgE-binding protein of 32 kd that was also recognized by antichitinase antibodies was detected in green bean extracts. This reactive component was strongly induced by ethylene treatment. The protein, designated PvChI, was identified as a class I chitinase closely related to the major avocado allergen Prs a 1. Immunoblot inhibition assays demonstrated cross-reactivity between both allergens. Purified PvChI induced positive skin prick test responses in 7 of 8 patients with latex-fruit allergy. Heat treatment of both Prs a 1 and PvChI produced a full loss of their allergenic capacities both in vitro and in vivo. No IgE-binding component was detected in the white mature bean in which the main isolated 32-kd protein corresponded to a nonreactive phytohemagglutinin. Conclusions: Ethylene treatment induces the expression of plant class I chitinases. The allergenic activity of plant class I chitinases seems to be lost by heating. This fact could explain why plant foods containing these putative allergens that are consumed after cooking are not usually associated with the latex-fruit syndrome.
ISSN: 0091-6749
DOI: 10.1067/mai.2000.107599
Source: Journal of Allergy and Clinical Immunology[ISSN 0091-6749],v. 106(1), p. 190-195 (Julio 2000)
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