Nasal, eye and respiratory allergies have traditionally been diagnosed by doing blood and skin tests for specific allergy to pollens, dust mites and pets. These test include Skin Prick Testing (SPTs) using allergens applied directly to the skin or RAST blood tests testing for systemic IgE antibodies travelling around the body in the blood stream. If these “systemic” allergy tests returned negative results, then one would diagnose these patients as being “non-allergic”, implying that an allergic cause for their condition was not present. However, up to 50% of people previously diagnosed as being non-allergic with negative tests have now been found to be allergic. The allergic reaction in these cases remained localised in the eye, nose and lower airways and the reaction did not spill over into the circulation, hence their blood tests and skin test remained negative. Recent research has shown localised IgE antibody production actually occurs on the surface of the eye conjunctiva, nasal membranes and airway bronchioles after exposure to pollens, dust mites and pet danders. It is more common in younger people with a family history of allergy (atopy). In the nose, Local Allergic Rhinitis (LAR) can only be diagnosed by measuring IgE antibodies in nasal mucus or by sniffing in the allergen and provoking a reaction, which causes measurable airway narrowing with swelling. These tests are not readily available outside medical research institutions and so are not yet accessible to general medical practice. So in the interim, we remain at a loss to confirm this type of localised allergic response, but do know it exists!
Reference: Campo R, Rondon C et al. Local IgE in non-allergic rhinitis. Clinical and Experimental Allergy: May 2015 (45) 872-881
