e-Poster 901 - Specific IgE testing with a NOVEOS analyser: comparison with immunoCAP and agreement with food allergy symptoms
B. Trouche-Estival (Institut Fédératif De Biologie, Hôpital Purpan, CHU de Toulouse, Toulouse, France), J. Milhes (Institut Fédératif De Biologie, Hôpital Purpan, CHU de Toulouse, Toulouse, France), Y. Lathrache (Institut Fédératif De Biologie, Hôpital Purpan, CHU de Toulouse, Toulouse, France), P. Apoil (Institut Fédératif De Biologie, Hôpital Purpan, CHU de Toulouse, Toulouse, France)
NOVEOS (HYCOR) is a new technology based on paramagnetic and fluorescent polystyrene microbeads (1µ) coupled to streptavidine, with biotinylated allergens kept in solution and detection of bound IgE by chimioluminescence.
A NOVEOS analyser was used to test serum samples which had previously been tested for various allergens between 2016 and 2020 with a PHADIA250 analyser. Samples were stored at -40°C before been thawed and analysed with NOVEOS. Some thawed samples were tested with ImmunoCAP reagent to verify that they were not altered by congelation and thawing.
We found no alteration of our samples due to thawing. A good to high correlation was found between ImmunoCAP and NOVEOS results, ranging from a mean value of 0.65 for airborne allergens (88 samples; d1, d2, e1, e5, g3, g6, m6, w9, t3, t215, t224), 0.78 for food allergens (125 samples) to >0.90 (cow’s milk and casein). Specific IgE results from NOVEOS were consistently lower than those from ImmunoCAP, with a mean bias of -25% (food allergens) to -30% (airborne allergens).
Next, we evaluated the correlation between NOVEOS results and the clinical status of food-allergic patients, whose allergy had been explored by single-blind oral food challenges. NOVEOS ROC curves were calculated for the following allergens: peanut extract (44 patients; AUC=0.84), rAra h 2 (0.88), egg white (33 patients; 0.72), ovomucoïd (0.74), cow’s milk (48 patients; 0.96), casein (0.91), and a combination of nuts allergens (21 patients; hazelnut, rCor a 14, cashew nut, rAna o 3, walnut; AUC: 0.89). ROC curves calculated from NOVEOS were all equivalent to curves deduced from ImmunoCAP data, and comparable to values reported in the literature.
Finally, we performed 47 specific IgE tests from 12 distinct UKneqas quality assessment samples (“specific IgE” and “allergen component” programs). These samples had previously been tested by ImmunoCAP and kept frozen at -40°C. We found that 90% of NOVEOS results were within the +/- 3 S.D. limit calculated from the “all methods” consensus reported by UKneqas.
NOVEOS can be used in a clinical laboratory setting and, for the food allergens we tested, will produce specific IgE results having the same clinical pertinence than those produced by ImmunoCAP. However, physicians must be informed that NOVEOS results are 25-30% lower than ImmunoCAP.