Evaluation of patatin as a major cross-reactive allergen in latex-induced potato allergy

Background: Potential cross-reactions between natural rubber latex and fruit/vegetable specific immunoglobulin (Ig)E antibodies have been reported for many years. This study was designed to investigate the molecular basis of acquired food sensitization focusing on the storage protein patatin and the patatin-like latex protein Hev b 7. Objective: The amount of potato-specific IgE in the serum of latex-allergic health care workers and children with atopic dermatitis was determined to evaluate cross-reactivity between Hev b 7 and patatin. Additionally, the stability of potato patatin to digestion was investigated. Methods: Human serum was tested on its reactivity to latex and potato proteins by IgE immunoblotting after one-dimensional (1-D) and 2-D electrophoresis. Latex- and potato-specific IgE concentrations were measured in fluorescence enzyme immuno-assays (CAP, Pharmacia, Uppsala, Sweden). Further, potato patatin was chromatographically isolated to perform auto-inhibition tests. Stability of patatin to degradation was determined by digestion in vitro. Results: Patatin was identified as major cross-reactive potato allergen by N-terminal sequencing. Seventy-five percent of the potato-sensitized people reacted with patatin in I-D immunoblots, and 25% of the positive reactions to Hev b 7 could be blocked by preincubation of the patients' sera with purified potato patatin. Examination of children with atopic dermatitis showed that most sera contained patatin-specific IgE, whereas no Hev b 7-specific IgE was detected. Finally, patatin has been found partially stable to digestion in vitro. Conclusions: Patatin was identified as a major cross-reactive protein in latex-associated potato allergy and appears to be relevant for atopic dermatitis. Therefore, patatin could be a suitable marker for the determination of potato sensitization, and it may also constitute an important food allergen. Cross-reactivity between Hev b 7 and patatin was restricted to primarily latex-sensitized adults, suggesting a different mechanism of sensitization in children with atopic dermatitis.