In the UK celery is listed as a top 14 allergen which needs to be labelled in packaged food.
There are 6 allergens associated with celery allergy – the main allergen in celery is Api g 1 which is similar in shape to the Bet v 1 allergens which can cause oral allergy type symptoms.
Two of the proteins found in celery are lipid transfer proteins, Api g 2 and 6.
I have put together some more comprehensive resources at http://www.allergyresources.co.uk/Celery.php
The allergy resources page for celery covers the key allergens, which allergic syndromes are linked to this allergy and other foods which are commonly cross reactive with celery.
There is also regularly updated links to useful websites specifically for celery allergies and the latest research papers on the topic.
If you have multiple allergies and are interested in how they are linked or want to find out more about food allergies outside the usual top 14 then you can follow me on Facebook or Twitter, where I share a food allergy card every day of the week.