Cross-reactions in the latex-fruit syndrome: A relevant role of chitinasesbut not of complex asparagine-linked glycans

Background: Cross-reactions between latex and plant foods (mainly fruits) h ave been widely reported. Although the cross-reactive components have not b een well identified, class I chitinases seem to be the most credible candid ates in chestnut, avocado, and banana. Objective: We sought to evaluate the potential role of chitinases and compl ex glycans as cross-reactive determinants linked to latex-food allergy, Methods: Extracts from 20 different plant foods and from latex were obtaine d, These preparations were immunodetected with anticomplex glycans and anti chitinase sera raised in rabbits, as well as with sera from patients with l atex-fruit allergy and sera from patients allergic to latex without food al lergy. Immunoblot inhibition assays were carried out by using a purified cl ass I chitinase from avocado or latex extract as inhibitors. Results: Reactive proteins of approximately 30 to 45 kd (putative class I c hitinases) were recognized by both specific polyclonal antibodies to chitin ases and sera from patients with latex-fruit allergy in chestnut, cherimoya , passion fruit, kiwi, papaya, mango, tomato, and flour wheat extracts. Prs a 1, the major allergen and class I chitinase from avocado, and the latex extract strongly or fully inhibited IgE binding by these components when te sted in immunoblot inhibition assays, Additional bands of 16 to 20 kd, 23 t o 28 kd, and 50 to 70 kd were detected by the antichitinase serum but not w ith the patients' pooled sera. The putative 30- to 45-kd chitinases present in different food extracts did not react with a pool of sera from subjects allergic to latex but not to fruit. Very different immunodetection pattern s were produced with the anticomplex glycan serum and the sera from allergi c patients. Conclusions: Putative class I chitinases seem to be relevant cross-reactive components in foods associated with the latex-fruit syndrome, but do not p lay a specific role in allergy to latex but not to fruit. Cross-reactive ca rbohydrate determinants are not important structures in the context of late x-fruit cross-sensitization.