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José Pedro Almeida1, Sara Prates2, Elena Finelli2, Miguel Paiva2, Pedro Martins2, Paula Leiria Pinto2

1 - Serviço de Imunoalergologia, Hospital de Santa Maria, Centro Hospitalar de Lisboa Norte, EPE, Lisboa
2 - Imunoalergologia, Área de Pediatria Médica, Hospital de Dona Estefânia, Centro Hospitalar de Lisboa Central, EPE, Lisboa

- EAACI Congress 2015, 6 a 9 Junho, Barcelona, Espanha; publicado sob a forma de resumo online no site da reunião

Introduction: In-vitro ImmunoCAP ISAC® (ISAC) allows the detection of specific IgE (sIgE) for a wide range of molecular allergens (MA). Our major goal was to analyze the pattern of sensitization to pollen MA by ISAC and assess the concordance between these and skin prick tests.
Methods: All patients with respiratory allergy (rhinitis and/or asthma) followed-up in our Department of Immunoallergology that performed the ISAC between 2012-2014, were retrospectively evaluated. Patients were submitted to: complete history taking, skin tests and ISAC.
Results: This study included 54 patients (28 males, 26 females), with a mean age of 22,7±12,9 years-old; 53 diagnosed with rhinitis and 27 with asthma. From the 54 ISAC tests, 85.2% showed sensitization to grass pollens, 42.6% to olive tree, 14.8% to plane tree, 13% to mugwort, 9.3% to wall pellitory, 7.4% to pigweed and 3.7% to birch.The grass pollens, olive tree and plane tree are represented by more than one MA. For grass, the most common were Cyn d 1 (87%), Phl p 1 (83%), Phl p 4 (54%), Phl p 2 (48%) and Phl p 5 (44%). The association of Cyn d 1, Phl p 2 and Phl p 5 allows the identification of 45 (out of 46) with positive ISAC, all with positive skin tests. In addition, Ole e 1 e Pla a 2 allow the identification of all patients with positive ISAC for olive tree and plane tree, correspondingly. The sensitization of cross-reactivity allergens was frequent (57%).Concerning the skin tests, the most frequent were grass (87%), olive tree (77.8%), birch (29.6%), plantain (27.8%), plane tree (25.9%) and wall pellitory (20.4%),The concordance analysis (Kappa (K)) between ISAC and skin tests has showed a substantial value related to grass (K=0.77), moderate for wall pellitory and plane tree (K=0.57; 0.43), and low for olive tree (K=0.21).
Conclusions: Overall, the usage of 3 MA of grass pollens may allow to identify the majority of sensitized patients. Concerning olive and plane trees, Ole e 1 and Pla a 2 are the allergens with best diagnostic capability. The moderate/low concordance between skin tests and ISAC for wall pellitory, plane and olive tree may reflect either sensitization to cross-reactivity MA, thereby leading to false positive results in the skin tests, or the absence of relevant putative allergens in the ISAC. One may assume that the quantification of selected MA as a replacement for of the ISAC may allow, at a lower cost, characterize the sensitization pattern and plan a targeted immunotherapy.

Palavras Chave: pollens, molecular allergens, ImmunoCAP ISAC