The Ficus-fruit-syndrome is a distinct entity not related to natural rubber latex allergy

Abstract

Rationale Ornamental Ficus benjamina (FB) is a new indoor allergen potentially associated with hypersensitivity to fig fruit ( Ficus carica). We evaluated the prevalence of sensitization and studied the cross-reactivity with other fruits and with Hevea latex. Methods A prick test solution from FB latex was tested in 4930 consecutive patients with suspect inhalant allergy. Patients positive to FB were further skin tested with exotic fruits by the prick-to-prick method. RAST inhibition using fig fruit as solid phase was performed in 11 patients with clinical fruit allergy. Results Among 2662 patients reacting to any aeroallergen, 66 (2.5%) reacted to FB. Ten patients showed isolated sensitization. Only 10.6% of FB-positive subjects were also positive to Hevea latex. Sensitization to FB was specifically associated with positive skin tests to fresh fig (83%), dried fig (37%), kiwi (28%), papaya (22%), avocado (19%), banana (15%), and pineapple (10%) (n=54). Clinical reactions were reported mainly from fresh and dried fig and kiwi (47, 60, and 64% of skin test-positive patients). Fig fruit RAST was inhibited 87% by FB, 89% by fresh fig, 80% by dried fig, 38% by kiwi, and 59 and 44% by the thiolproteases ficin and papain, respectively. No inhibition was obtained with Hevea latex and rHev b 6.02 (hevein). Conclusions Sensitization to FB latex is found in 2.5% of atopics and is largely independent of Hevea latex allergy. Sensitization is commonly associated with allergy to figs and other tropical fruits (“Ficus-fruit syndrome”). This cross-reactivity is mediated, at least in part, by thiolproteases but not by hevein-like allergens.