Evaluation of High Speed Laser Doppler Imaging Technology (HSL-DI)

Evaluation of High Speed Laser Doppler Imaging Technology to Quantify Skin Prick Tests in Allergic Volunteers

Skin prick tests (SPT) are commonly used in daily allergological practice to assess skin reactivity to allergens. Multiple factors can contribute to non-optimal results of conventional wheal and flare measurement (CWFM) of SPT such as inaccurate measurements, observer-dependency and absence of traceability. This study aims to evaluate the quantification of SPT by a novel High Speed Laser Doppler Imaging (HSL-DI) and to compare it with CWFM. First, SPT with birch and/or grass pollen extracts as well as positive and negative controls will be performed in 20 volunteers (11 atopics, 9 non-atopics) to establish the characteristics (cut-off, optimal reading time and allergen concentration) of HSL-DI analysis based on two parameters ("area" and "flow" measurement). In a second step, fifty patients will be tested with birch and grass pollen extracts at optimal allergen concentration and time window. Analysis of SPT by HSL-DI and CWFM will be compared.

Allergy tests will be performed in allergic patients with rhinoconjunctivitis and allergy test reading measured following two different methodologies. 1) test reading based on conventional wheal and flare measurement (wheal diameter in mm, CWFM), 2) test reading based on high speed laser doppler imaging (HS-LDI). Both type of tests reading will be compared.

Reading of allergy skin tests (in response to allergen extracts or histamine or negative control) by HSL-DI versus direct observer evaluation (CWFM)

Skin microcirculation flow changes will be evaluated at 2.5 min., 5 min., 7.5 min., 10 min., 12.5 min., 15 min., 17.5 min. and 20 min. as measured in a composite outcome 1) by HS-LDI based on parameter "area" corresponding to the total number of non-zero pixels in the flare area and parameter "flow" as measured according to a specific formula in arbitrary units, or 2) as measured by conventional wheal and flare measurement (CWFM, direct observer reading) in mm.

Inclusion Criteria: age 18 to 65 years history of allergic rhinitis to birch pollen and/or grass pollen. Exclusion Criteria: any medical condition (including pregnancy) that could influence the study (viral or bacterial airway infection, active allergic rhinitis) uncontrolled asthma (peak expiratory "flow" <80% of volunteer's best personal value) treatment with antihistamine medication less than two weeks before enrolment or during the trial.