Evaluation of the applicability of the Immuno-solid-phase allergen chip (ISAC) assay in atopic patients in Singapore.
OBJECTIVE
Molecular-based allergy diagnostics are gaining popularity in clinical practice. Our aim was to evaluate their role in the tropics, given the inherent genetic and environmental differences.


METHODS
We recruited subjects with history of atopy and collected data on demographics and atopic symptoms using validated questionnaires. Subjects underwent a series of skin prick tests (SPT). Serum total and specific IgE levels were measured using ImmunoCAP FEIA and ImmunoCAP ISAC®, respectively. We describe their pattern of sensitization and agreement between test methods.


RESULTS
A total of 135 subjects were recruited; mean ± SD age of 31.18 ± 12.72 years, 52.7% female. Allergic rhinitis (AR) was the most prevalent clinical manifestation of atopy (70.7%), followed by atopic dermatitis (AD) (50.5%) and asthma (26.2%). Polysensitization was seen in 51.1% of subjects by both SPT and ISAC. House dust mites (HDM) were the dominant allergen, with sensitization in 67.8% and 62% of subjects on SPT and ISAC, respectively. A group of subjects with monosensitization to B. tropicalis was identified. HDM sensitization was strongly associated with AR, while AD and asthma were not associated with sensitization to any allergen. Agreement between SPT and ISAC was mostly suboptimal. Greatest agreement was documented for the measurement of HDM sensitization with both methods (κ = 0.64). Sensitization to the bulk of the remaining allergens in the ISAC panel was infrequent.


CONCLUSIONS
Multiplex methods should not be used as a screening tool, especially in a population with lower rates of polysensitization and a dominant sensitizing allergen. There may be a role in adjusting the antigen spectrum in the ISAC panel to regional differences.
Division of Rheumatology, University Medicine Cluster, National University Health System, Singapore, Level 10 Tower Block, 1E Kent Ridge Road, Singapore, 119228 Singapore ; Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore, 117597 Singapore.
Amelia
A
Santosa
SIgN (Singapore Immunology Network), ASTAR (Agency for Science, Technology and Research), Singapore, Singapore.
Anand Kumar
AK
Andiappan
SIgN (Singapore Immunology Network), ASTAR (Agency for Science, Technology and Research), Singapore, Singapore.
Olaf
O
Rotzschke
Yong Loo Lin School of Medicine, National University of Singapore, 10 Medical Drive, Singapore, 117597 Singapore.
Hung Chew
HC
Wong
Department of Pharmacy, National University Health System, Singapore, Singapore.
Amanda
A
Chang
IMB (Institute of Medical Biology), ASTAR (Agency for Science, Technology and Research), Singapore, Singapore.
Mei
M
Bigliardi-Qi
Department of Otolaryngology, National University of Singapore, Singapore, Singapore.
De-Yun
DY
Wang
Division of Rheumatology, University Medicine Cluster, National University Health System, Singapore, Level 10 Tower Block, 1E Kent Ridge Road, Singapore, 119228 Singapore ; IMB (Institute of Medical Biology), ASTAR (Agency for Science, Technology and Research), Singapore, Singapore.
Paul Lorenz
PL
Bigliardi
Atopy; ISAC; Sensitization; Skin prick test; Specific IgE