NEW YORK CITY—Latex allergy is commonly accompanied by cross-reactivity to fruits, particularly avocados, bananas, or kiwi. This so-called latex fruit syndrome is usually asymptomatic, but it may involve clinically relevant allergic reactions and anaphylaxis.

But which came first, the allergy to latex or to fruit? Should patients with the latex fruit syndrome avoid all cross-reacting foods? Is immunotherapy effective for their latex allergy? An expert panel addressed these questions during a symposium on latex fruit syndrome at the recent annual meeting of the American Academy of Allergy, Asthma, & Immunology in New York City.[1]

Evidence suggests that latex allergy precedes fruit allergy in patients with the latex fruit syndrome. First, the reported incidence of food allergy in latex-allergic patients is as high as 52%—much greater than the 11% rate of latex allergy in food-allergic patients, noted Dr. Sussman.

Also, in immunoblot inhibition studies, cross-reactivity could be demonstrated between latex and several potato proteins in 47 patients with latex allergy but not in 46 controls without latex allergy.[2] Another important finding of this study: 33 patients, but only seven controls, had positive skin tests for various fruits and vegetables. Sensitivity manifested as significant allergic reactions in 17 patients and included anaphylaxis in 11 cases.

When latex-allergic individuals react to foods that do not usually cause a problem, inadvertent contamination from a food handler’s latex gloves should be suspected. This mode of latex exposure has only recently been recognized and may not necessarily be obvious, Dr. Sussman said. In vitro tests showing the transfer of latex proteins from latex gloves to cheese and other foods support its feasibility.

Any food that causes clinically relevant allergic reactions or anaphylaxis should obviously be avoided. However, some patients may display sensitivity to some foods during testing yet not experience symptoms when they consume those foods. These patients should be advised that they can eat cross-reacting foods but should exercise caution when doing so, Dr. Sussman suggested; attempting to completely avoid the foods may result in so many dietary restrictions that nutrition is compromised.

PROTEIN CULPRITS

Latex contains about 240 proteins, 57 of which are known allergens. However, Hevea brasiliensis (Hev b) proteins 5, 6, and 7 are the proteins most often associated with cross-reactivity in latex-allergic patients, pointed out Randolf Brehler, MD, a dermatologist at the Health Clinic University in Münster, Germany.

Skin tests containing natural fractions of Hev b proteins 1 through 7 have proved reasonably sensitive in detecting latex allergy. Those made with recombinant Hev b proteins 5, 6, and 7 are about 93% sensitive.

Diagnostic accuracy also appears to be excellent with a new “spiked” latex allergen. “This is a natural extract from latex that is spiked with recombinant Hev b 5,” Dr. Brehler explained.

Natural latex extract was also recently used for specific immunotherapy in a randomized, double-blind, placebo-controlled trial involving 17 patients with latex skin allergy and rhinitis (nine of these patients also had asthma).[3] One year of treatment significantly improved rhinitis, conjunctivitis, and cutaneous symptoms; decreased allergen-specific conjunctival reactivity; and reduced the need for latex allergy medications.

“But, natural allergen extracts are difficult to standardize … and we can have anaphylactic side effects,” remarked Dr. Brehler. Recombinant allergens may be preferable, he said, because they are highly standardized and reproducible in large quantities, and they have low immunoglobulin E (IgE) binding capacity.

Another emerging approach to specific immunotherapy for latex allergy involves treatment with T-cell epitope containing latex peptides in which the IgE epitope has been destroyed. Similar peptides derived from cat allergens have shown some ability to improve cat allergies in clinical studies,[4] and it is hoped the same may be true for the latex-derived peptides in the treatment of latex allergy.

—Timothy Begany

References
1. Fink JN, Blanco C, Brehler R, Sussman GL. Latex and food allergy—the latex fruit syndrome. Presented at: American Academy of Allergy, Asthma, & Immunology 58th Annual Meeting; March 2, 2002; New York, NY.
2. Beezhold DH, Sussman GL, Liss GM, Chang NS. Latex allergy can induce clinical reactions to specific foods. Clin Exp Allergy. 1996;26:416-422.
3. Leynadier F, Herman D, Vervloet D, Andre C. Specific immunotherapy with a standardized latex extract versus placebo in allergic healthcare workers. J Allergy Clin Immunol. 2000;106:585-590.
4. Simons FE, Imada M, Li Y, et al. Fel d 1 peptides: effect on skin tests and cytokine synthesis in cat-allergic human subjects. Int Immunol. 1996;8:1937-1945.

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