Allergy testing on the IMMULITE 2000 Random-Access immunoanalyzer - a clinical evaluation study

Purpose: We aimed to evaluate the diagnostic performance of the IMMULITE 2000 Allergy System from Diagnostic Products Corporation (DPC) for the detection of inhalant and food allergies, focusing on inhalant and food screens, mixes and single allergens. Methods: Serum samples were collected from new, unselected patients who were referred to the allergist for a suspected allergy. Patients were classified as study diagnosis-positive for inhalant (food) allergy if they had both a positive clinical examination/history and a positive skin test for inhalant (food) allergy; otherwise - failing one or both of these criteria - they were classified as study diagnosis-negative. Classification and testing of the serum samples was carried out in a blinded fashion. Values greater than 0.35 kU/L were considered positive. Results: Of the 118 patients included, 63 were considered study diagnosis-positive for inhalation and/or food allergy. DPC inhalation screening showed 82% total agreement (TA) and 91% sensitivity relative to the study diagnoses. The DPC food panel showed 96% TA and 98% specificity relative to the study diagnoses. Relative to specific intracutaneous testing (ICT), the DPC D1, E1 and E5 assays had sensitivity of 82-90%; tree and grass panels had sensitivity of 74% and 95%. The DPC weed panel and initial lots of DPC E5 had poor sensitivity (< 40%); mold panel sensitivity was equally low for both DPC and the routinely used Pharmacia assay (36%). Relative to skin prick testing (SPT), specific food allergens had TA of 94-98% and specificity of 95-100%. Conclusion: In patients classified by the combination of clinical examination/history and skin test results, the DPC IMMULITE 2000 Allergy System generally demonstrated acceptable sensitivity, specificity and TA compared to the study diagnoses, both at the screening level and at the level of panels and single allergens.