"Pollen-food Allergy syndrome (PFAS) " is a term used when in a patient, sensitized to pollen, allergic symptoms are triggered by the ingestion of fruits or vegetables that have cross-reactivity with pollen antigens. Clinical symptoms mostly localize to the oral cavity, and then can be referred to as "Oral allergic syndrome (OAS). " However, a small subset of patients does not only have OAS but also systemic symptoms, which may lead to anaphylaxis.

Medical history is paramount in PFAS diagnosis. PFAS patients have histories of pollinosis and of experiencing symptoms when eating fresh fruits and vegetables, though not when eating processed foods. Plant molecules well-known for their involvement in PFAS are Bet v 1 homologues, and there also has been a recent interest in profilin and GRP. Unfortunately, only a few types of PFAS allergens are available as recombinant proteins. Therefore, auxiliary diagnosis is mainly performed by prick-to-prick tests that use food itself. Because there are allergenic differences between fruits and vegetables depending on their variety, site, and maturity, it is imperative to further develop standardized test reagents for improvement of PFAS diagnosis.