Can component-based microarray replace fluorescent enzimoimmunoassay in the diagnosis of grass and cypress pollen allergy?

BACKGROUND

Few data on the diagnostic accuracy in pollinosis of the microarray ISAC of allergens are available.

OBJECTIVE

We aim to comparatively analyse ISAC CRD103 with the whole-extract ImmunoCAP in grass and cypress pollen allergy, evaluating the suitability of the manufacturer's recommended cut-off points for both techniques.

METHODS

We studied 120 atopic patients grouped into grass and cypress pollen-allergic patients and controls based on clinical history and skin prick tests. Specific IgE against Phleum pratense and Cupressus arizonica by ImmunoCAP and ISAC CRD103 were performed on all subjects.

RESULTS

In the grass pollen group (43 allergic/26 controls), both microarray and CAP showed high sensitivity (Se) and specificity (Sp) values (ISAC: Se 97.7, Sp 92.3; CAP: Se 95.3, Sp 96.1) for recommended cut-off points. Comparing the optimal (ISAC: 0.4 ISU; CAP: 0.33 kU/L) with the recommended cut-off points within the same technique, diagnostic agreement was observed in both techniques. Thus, CAP and ISAC showed similar diagnostic performance in grass pollen allergy when using recommended cut-off points. In cypress pollen group (12 allergic/92 controls), the microarray (Se: 91.7, Sp 91.3) showed similar Se but significantly higher Sp (P=0.034) than CAP (Se: 91.7, Sp: 80.4) using recommended cut-off points. However, although diagnostic performance of the microarray did not change when comparing the optimal (0.82 ISU) with the recommended cut-off point, CAP improved diagnosis of cypress pollen allergy, when applying the optimal (0.66 kU/L)(CAP Se: 91.7, Sp: 89.1) instead of the manufacturer's recommended cut-off point. Thus, when the most suitable cut-off point for both techniques (ISAC: 0.3 ISU; CAP: 0.66 kU/L) is selected, microarray and CAP provide equivalent diagnoses.

CONCLUSIONS AND CLINICAL RELEVANCE

Component-based microarray ISAC CRD103 and whole-allergen CAP showed high Se and Sp diagnosing equally grass and cypress pollen allergy. The cut-off point for each allergen should be properly applied for both techniques.