Allergy to apple, carrot and potato in children with birch pollen allergy.

Skin sensitivity to apple, carrot and potato, clinically related to birch pollinosis was investigated. Different skin test techniques using fresh fruit were compared. A simple prick test (SPT) technique with a lancet piercing the apple peel just before pricking the skin was shown to be the most practical and to give reproducible results. The allergenic activity in apple was found to be heat labile and deteriorated during storage at room temperature. Apple, carrot, potato, hazelnut and birch reactivity was transferable in Prausnitz-Küstner test like IgE antibodies. SPT reactivity to fresh material from apple, carrot and potato was investigated in 174 children of whom 128 suffered from pollen allergy. Positive SPT results were obtained almost exclusively in children who were SPT positive to a birch pollen extract. Children who noticed clinical symptoms when eating apple, raw carrot or potato were found to have a significantly larger SPT reaction than children with a negative history.