We compared the performances of 3 simultaneous multiple allergen test (MAST) assays: RIDA Allergy Screen (R-Biopharm, Darmstadt, Germany), MAST Optigen allergy system (Hitachi Chemical Diagnostics, Mountain View, CA) and Polycheck Allergy (Bio check GmbH, Münster, Germany). Forty RIDA Allergy Screen positive sera (20 for food and 20 for the inhalant panel) were subjected to MAST Optigen and Polycheck Allergy.
For 26 available sera with discrepant results, 62 ImmunoCAP allergen-specific IgE tests (Pharmacia Diagnostics, Uppsala, Sweden) were performed. The percentage agreements (kappa value) were 87.6% (0.59) and 91.3% (0.60) between RIDA and MAST; 89.9% (0.55) and 88.3% (0.46) between RIDA and Polycheck; and 86.8% (0.51) and 90.6% (0.61) between MAST and Polycheck.
Compared with ImmunoCAP, the concordances (kappa value) of the inhalant and food panels were 51.7% (0.04) and 33.3% (−0.38) for RIDA; 60.7% (0.27) and 81.8% (0.59) for MAST; and 65.5% (0.26) and 45.5% (0.07) for Polycheck.
The concordances between RIDA, MAST and Polycheck and ImmunoCAP-positivity were 45.7%, 88.2%, and 28.6%, respectively, and the concordances for ImmunoCAP-negativity were 37.0%, 51.9%, and 88. 9%. MAST Optigen showed better agreement with ImmunoCAP than with other assays in the food panel. Better sensitivity of MAST Optigen and better specificity of Polycheck Allergy were suspected.
Material And Methods
- RIDA allergy screen
250 uL of patient serum was added to the reaction wells of each of the inhalant and food panels containing 39 types of allergens. After 45 min of incubation at room temperature and washing, 250 uL of biotin-labelled anti-IgE was added. After 45 minutes of incubation at room temperature and washing, 250 uL of streptavidin conjugate was added.
At twenty minutes of incubation at room temperature and washing, 250 uL of luminescent reagent was added. After 20 minutes of incubation, the results were scanned with a CCD camera (RIDA X-Screen Reader) and interpreted as class 0–6. Class ≥1 was interpreted as positive.
- Allergy to politicking
After washing the cassette of inhalants and foods containing 39 types of allergens, 250 uL of starting solution was added. After 60 seconds of incubation, 200 uL of patient sera were added. After 1-hour incubation on a shaker, 6 washes were carried out. Anti-IgE was added and a 45 minute incubation was carried out on a shaker.
After 3 washes, 250 uL of the enzyme-labelled conjugate was added. After 20 minutes of incubation and washing, 250 uL of luminescent reagent were added. After 20 minutes of incubation, the results were scanned and interpreted with Bio check Image Software as class 0–6. Class ≥1 was interpreted as positive.
- MAST Optigen
Patient sera were added to MASTpette chambers containing 35 types of allergens. After 2 hours of incubation and washings, enzyme-labelled anti-IgE was added. After 2 hours of incubation and washings, a luminescent reagent was added. After 10 minutes of incubation, the results were interpreted as class 0-4 with the MAST Optigen luminometer. Class ≥1 was interpreted as positive.
- ImmunoCAP IgE System Specific for Allergens
All procedures were performed following the manufacturer’s instructions. The detection range of ImmunoCAP FEIA was 0.1 to 100 km / L. The sIgE rating scales were as follows: class 0: less than 0.35 km / L, class 1: 0.35–0.7 kU / L, class 2: 0.7–3.5 kU / L , class 3: 3.5–17.5 kU / L, class 4: 17.5–50 kU / L, class 5: 50–100 kU / L, class 6: more than 100 km / L. Class ≥1 was interpreted as positive.
- Statistic analysis
The concordance of the detection results was analyzed (Cohen’s kappa analysis). We evaluate and categorize the Kappa value as near perfect (0.8–1.0), substantial (0.6–0.8), moderate (0.4–0.6), fair (0.2–0.4), and poor (below 0.2). We calculate three different percentages of agreement (positive, negative, and total agreement percentages).
The percentages of the positive and negative agreement were calculated with the proportions of the agreement for the average of their positive and negative responses. The percentage of total agreement was calculated as follows: (total number of results – number of discrepancies) × 100 / total number of results.