Beware of natural fruit and nut ingredients in latex-allergic patients

It has been 40 years since the first reported case of IgE-mediated natural rubber latex allergy, which was soon followed by a global epidemic of allergic and anaphylactic reactions.^1,2 Resolution came through insightful work in the 1990s that led to the removal of cornstarch powder and a switch to nonpowdered latex and synthetic examination gloves.² Also discovered during this period was the cross-reactivity of many patients to latex and various fruits. This column will briefly discuss the latex/fruit allergy syndrome, which should be considered in patients who are sensitive to various skincare products.

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Research substantiates reports

Blanco et al. conducted a prospective study in their outpatient clinic in 25 patients diagnosed with latex allergy, published in 1994.They used a clinical questionnaire, skin-prick tests, skin test with a latex extract, and identification of total and specific IgE to help ascertain clinical characteristics and cross-reactivity. Of the 23 women and 2 men in the study (mean age 33, plus or minus 9 years), 9 (36%) experienced latex-induced reactions characterized by systemic anaphylaxis. In 13 patients (52%), 42 food allergies were identified, and 23 included systemic anaphylaxis. Avocado (9), chestnut (9), banana (7), kiwi (5), and papaya (3) were the most common foods to cause hypersensitivities. The researchers concluded that their small study supported the reality of a “latex-fruit syndrome.”³

Another study aimed to characterize the cross-reactivity of latex and foods and evaluate clinical significance. Beezhold et al. examined 47 patients allergic to latex and 46 nonallergic controls. The investigators found immunologic reactivity to foods to be prevalent (33 latex-allergic patients and seven controls), with 27% of food skin-prick tests positive in the latex-allergic group. In addition, clinical symptoms were linked to 27% of positive skin-prick tests. Among the 17 patients who displayed clinical allergies to at least one food, 14 showed local sensitivity reactions, with anaphylaxis noted in 11. Avocado (53%), potato (40%), banana (38%), tomato (28%), chestnut (28%), and kiwi (17%) were the foods most frequently cited for provoking a skin test reaction. The authors observed extensive cross-reactivity between latex sensitivity and particular foods, with potatoes and tomatoes reported for the first time.⁴

In 1997, Brehler et al. studied serum samples from 136 patients whose immediate hypersensitivity to latex proteins was clinically observable and documented. The samples were assessed for IgE antibodies against several fruits, with fruit-specific IgE antibodies recorded in 69.1%. Radioallergosorbent (RAST) -inhibition tests yielded the recognition of cross-reacting IgE antibodies in latex and multiple fruit allergens: avocado, banana, chestnut, fig, kiwi, mango, melon, papaya, passion fruit, peach, pineapple, and tomato. The investigators recorded 112 intolerance reactions and noted that 42.5% of their patients reported allergic symptoms after consuming these fruits. Fruit-specific IgE antibodies were detected in only 32.1% of these patients, suggesting to the researchers that serologic tests were suboptimal in forecasting food hypersensitivities in patients who are allergic to latex.⁵

Cross-reactivity with banana

Mäkinen-Kiljunen studied 47 patients to investigate banana allergy in patients with latex allergy in 1994, measuring latex-, banana-, and pollen-specific (birch, timothy, and mugwort) IgE. Thirty-one patients were also given skin-prick tests with banana and were queried about reactions after consuming bananas. Of the 47 sera samples, latex RAST results were positive in 31 and banana RAST results in 26. RAST results from latex and banana were correlated (25 of the 31 latex RAST-positive samples were also banana RAST-positive), but not with pollen. Sixteen of the 31 patients who ate banana reported symptoms, and 11 of the 31 patients given the banana skin-prick test showed positive results. The author confirmed the cross-reactivity of IgE antibodies for latex and banana, identifying for the first time a structurally similar antigen/allergen as at least one antigen from banana fused with an antigen from latex in crossed-line immunoelectrophoresis.⁶

In 1998, Mikkola et al. investigated whether proteins similar to hevein, a major natural rubber latex allergen, are present in banana and account for cross-reactivity between these botanicals. Immunoblotting revealed that 9 of 15 sera from latex-allergic patients with IgE to hevein also bound to 32- and 33-kd banana proteins. Studies using ELISA [enzyme-linked immunosorbent assay] showed that the common presentation of hypersensitivity to banana among patients allergic to latex could be attributed to cross-reacting IgE antibodies binding to epitopes in hevein and in the then-newly identified hevein-like endochitinase found in banana.⁷