Positive skin and oral challenge responses to potato and occurrence of immunoglobulin E antibodies to patatin (Sol t 1) in infants with atopic dermatitis

The clinical significance and molecular specificity of hypersensitivity reactions to raw and cooked potatoes remain ambiguous. We therefore investigated the clinical hypersensitivity to raw and cooked potato in infants suspected to have potato allergy and compared the findings with the occurrence of immunoglobulin E (IgE) antibodies to patatin (Sol t 1), characterized as the primary allergen of potato. Twelve infants (10 to 24 months of age) suffering from atopic dermatitis (AD) and suspected to have adverse reactions to potato, were examined. As a skin exposure test we used rubbing with both raw and cooked potato, and used open oral challenge with cooked potato for 7 days. A special eczema scoring system (SCORAD) was used to assess the severity of symptoms and signs of AD. Skin-prick tests (SPTs) were performed with raw potato and natural Sol t 1, and serological studies included measurement of total serum IgE and IgE antibodies to Sol t 1, and potato radioallergosorbent testing (RAST). The skin-rubbing test with raw potato was positive in seven (58%) and the oral challenge positive in eight (67%) infants. One infant presented with an immediate reaction and seven with a delayed reaction, i.e. exacerbation of AD, after oral challenge responses to cooked potato. Nine (75%) infants had IgE antibodies to Sol t 1 in enzyme-linked immunosorbent assay (ELISA), and SPT to natural Sol t 1 was positive in six (50%) potato-allergic infants. In conclusion, we observed positive challenge responses to both raw and cooked potato in food-allergic atopic infants. The presence of IgE antibodies and concomitant positive SPTs to the heat-stable potato allergen, Sol t 1, suggest that cooked potato can be an allergenic food for infants suffering from AD.