DIAGNOSIS OF ALLERGY: IgE MEDIATED CROSS-REACTIONS AMONGST SELECTED ASTHMA ELICITORS

IgE mediated allergic reactions to various foods such as fish, nuts, some fruits and vegetables are very common in both children and adults worldwide. Diagnoses of allergies particularly bronchial asthma, allergic rhinitis, urticaria and atopic dermatitis are generally conducted in vivo as Skin Prick Test (SPT) using different allergenic extracts. Review of data from various international publications on allergy related journals show that majority of allergic patients are diagnosed as mono-sensitized. The research was aimed at reviewing cross-reactivity pattern in SPT between various ingestant and inhalant allergens and its specific objective is the cross-reactivity between food items and pollen, fruits and pollen, vegetables and pollen as well as seafood and indoor allergens. The major identified proteins for each allergen were included.

The review of the data on SPT, cross-reactivity and the major protein, exhibit cross-reactivity between majority of common food items and pollen grains. The data also revealed 5 major proteins namely, profilin, Lipid Transfer Proteins (LTP), Pathogenesis-Related (PR) Protein, Tropomyosins and albumin in majority of allergens. The first 3 proteins were commonly shared by majority of food and pollen. The last 2 proteins were shared between the seafood and indoor allergens. It is therefore not inconceivable that the majority of poly-sensitizations are cross-reactivity of the major proteins found in all such allergens.

Clinical diagnosis in both adults and children are difficult as a result of cross-reactivity. The cross-reactivity does not confirm the primary sensitizer(s) but induces IgE mediated skin reactivity by allergens containing similar protein(s). The choice of allergens for immunotherapy should be carefully evaluated with possible cross-reacting allergens.