[Rules concerning allergy to celery (and other Umbellifera)].

1. Allergy to celery is associated with a pollinosis. Even if there are no overt symptoms of the pollinosis there are positive tests, including RAST. 2. The causative pollen is usually the most common of the region, for example in Sweden it is birch (Betula), whilst in the surroundings of Lyon in France ragweed (Ambrosia) and mugwort (Artemisia) and Compositae in general seem to play a particularly important role. 3. The allergy is strictly on-way, celery-pollen. If the reverse should occur the positive tests for celery are often found when allergy is caused by ragweed or mugwort. 4. Other Umbelliferae such as parsley and carrots produce the same effects. 5. The syndrome seems to implicate aromatic plants for culinary use. 6. The allergen has been shown to be heat-stable and this indicates that it is a small molecule.