Tomato allergy: clinical features and usefulness of current routinely available diagnostic methods

Tomato contains many allergens but their clinical relevance is poorly defined and the usefulness of available diagnostic methods is unknown.

To assess the clinical usefulness of current diagnostic methods for tomato allergy.

Ninety-six adults with plant food allergy were grouped based on their reactivity to PR-10, profilin, and lipid transfer protein (LTP). Tomato allergy was ascertained by history and a positive skin prick test (SPT) to fresh tomato. SPT with a commercial extract and immunoglobulin (Ig) E measurements were carried out.

In total, 36%, 8%, 28%, 18%, 8%, and 1% of patients were sensitized to PR-10, profilin, both PR-10 and profilin, LTP alone, LTP plus PR-10 or profilin, and genuine tomato allergens, respectively. Tomato allergy was detected in 32 (33%) of the 96 patients and was significantly associated with profilin hypersensitivity (P < .001). The sensitivity of SPT was good in all subgroups, but specificity was poor in many cases. ImmunoCAP sensitivity was acceptable in profilin reactors, but very poor in PR-10 reactors. IgE levels were not associated with tomato allergy in any of the subgroups. Similarly, birch and peach-specific IgE levels were not associated with tomato allergy in PR-10/profilin or in LTP reactors, respectively. Both SPT and ImmunoCAP worked well in the only patients with true tomato allergy. Birch- and tomato-specific IgE levels were not associated in patients monosensitized to PR-10, but they were correlated in profilin groups (P < .005). Peach- and tomato-specific IgE levels were correlated (P < .001) in LTP-allergic patients.

Tomato allergy occurs via sensitization towards different proteins. Component-resolved diagnosis helps to define clinical subgroups with different risk levels.