ImmunoCAP and HY.TEC enzyme immunoassays in the detection of allergen-specific IgE compared with serial skin end-point titration by receiver operating characteristic analysis

OBJECTIVES: In this study we compared 2 different immunoassays, HY IEC enzy me immunoassay (Hycor Biomedical Inc, Garden Grove, CA) and Pharmacia Upjoh n ImmunoCAP (Pharmacia and Upjohn, Kalamazoo, MI) using skin end-point titr ation as a gold standard by receiver operating chatacteristic analysis. MATERIALS: One hundred patients were enrolled in this study and were tested with the above 3 modalities. The results were analyzed by receiver operati ng characteristic analysis, in which the curves give a decision criterion f or any diagnostic test relative to its sensitivity and specificity against an accepted gold standard test. Only inhalant allergens (Dermatophagoides p teronyssinos, Dermatophagoides farina, cat dander, giant ragweed, English p lantain weed, timothy grass, Alternaria tenuis, Aspergillus fumigatus, mead ow fescue, oak tree, white ash tree, and lamb's-quarter weed) were studied. RESULTS: The results obtained with both ImmunoCAP and HY.TEC showed a good correlation with skin end-point titration for D pteronyssinus, D farina, ca t dander, giant ragweed, timothy grass, A tenuis, and meadow fescue, with s ensitivities ranging from 71% to 88%. However, the sensitivity of both test s to English plantain weed, lamb's-quarter weed, oak free, and white ash tr ee was lower (66% down to 39%). Additionally, HY.TEC results were not satis factory for detecting specific IgE to A fumigatus (30% sensitivity). The ov erall sensitivity for each test was 65.67% for the HY.TEC and 71.25% for th e ImmunoCAP. CONCLUSION: The 2 in vitro testing systems are comparable for most of the a llergens, except for A fumigatus, English plantain, lamb's-quarter, and whi te ash tree; ImmunoCAP and HY.TEC would benefit from improved technology fo r detecting these specific IgE antibodies. The HY.TEC assay did not give ac ceptable results for A fumigatus. The overall assay characteristics were go od to excellent for each system tested.