A Real Life Comparison between Allergenic Extracts and Allergenic Molecules.

Serum IgE assay is a mainstay step in the allergy work up. Allergenic extracts and molecular components are available at present. This real life study compared the serum specific IgE levels against allergenic extracts with allergenic molecules in patients allergic to Parietaria, Betulaceae, and mites. This retrospective real life study included 489 subjects with respiratory allergy. Inclusion criteria were 1) documented diagnosis of allergic rhinitis (AR) and/or allergic asthma, and 2) documented allergy to Parietaria judaica (Par j) 2 (216 patients: 112 females, mean age 42 years), or to Betula verrucosa (Bet v) 1 (62 patients: 35 females, mean age 3 years), or Dermatophagoides pteronyssinus (Der p) 1 (211 patients: 107 females, mean age 34 years); and mono-allergy. Serum IgE, specific both for total/crude allergen extracts and individual purified/recombinant allergens, were assessed by ImmunoCap system. The serum IgE levels to birch extract were very strongly (R2=0.96) related to IgE to Bet v 1. There was a strong (R2=0.71) correlation between Dermatophagoides pteronyssinus IgE and Der p 1. A very strong (R2=0.87) correlation also existed between Parietaria extract IgE and Par j 2 IgE levels. However, there was discrepancy between percentages of positivity between allergenic extracts and molecules. Therefore, allergen molecular diagnostics may represent a useful way in allergy work up, but deserves caution in particular circumstances.