Delayed allergic reaction to eating lemon: case report.

Allergy to lemon can be caused by both IgE-mediated and IgG-dependent mechanisms, or have a combined IgE/IgG-dependent origin. For the first time, a clinical case of a combined immediate and delayed allergic reaction to eating lemon, which manifests itself in the form of oral allergic syndrome and gastrointestinal symptoms, in a 31-year-old woman was described. The patient was diagnosed with polysensitization to various food, household and pollen antigens, cross-allergy to fruits of the Rutaceae family (orange, tangerine, grapefruit). With the help of a prick+prick test and an enzyme-linked immunosorbent assay, she was diagnosed with allergy and sensitization to the allergens of lemon pulp. The presence of one or more thermolabile antigens in lemon pulp, causing immediate and delayed allergy symptoms, has been established. The ability of thermolabile allergens and/or individual antigenic determinants to induce delayed allergic reactions, despite the action of proteolytic enzymes of the gastrointestinal tract and hydrochloric acid, has been established. To establish the resistance of individual antigenic epitopes of lemon allergens to the effects of various factors of the gastrointestinal tract, additional studies are required to establish the sensitivity of protein molecules of allergens to these factors.