Sensitization to house dust mite allergens might be related to the low sensitivity of ImmunoCAP to pollen allergen.

BACKGROUND

Skin prick test (SPT) and ImmunoCAP are widely used to diagnose allergies. However, previous studies showed discordance between the results of SPT and ImmunoCAP and there remains a lack of research to better understand the differences in results between the two tests.

OBJECTIVE

We investigated factors that affected the discordance between SPT and ImmunoCAP results.

METHODS

We reviewed the medical records of 94 subjects who underwent both SPT and ImmunoCAP for six allergens (Dermatophagoides pteronyssinus, Dermatophagoides farinae, alder, ragweed, mugwort, and Humulus japonicus). We retrospectively analyzed whether age, sex, body mass index, and allergic sensitization to house dust mite (HDM) or seasonal allergens affected the discordance of results between SPT and ImmunoCAP.

RESULTS

The positivity rates for HDM allergens were similar between the two tests. For seasonal allergens, however, the positivity rates were much higher in the SPT than those in the ImmunoCAP. The concordance rates of the two tests were relatively higher for HDM than seasonal allergens. Moreover, the ratio of the subjects positive by SPT and negative by ImmunoCAP was higher for seasonal allergens. Positivity for HDM allergens by SPT resulted in a higher rate of mismatch between the two tests for seasonal allergens.

CONCLUSIONS

The ImmunoCAP test for seasonal antigens showed low positivity rates compared to SPT in cases positive for HDM allergens. This suggests that the results of ImmunoCAP are less sensitive for seasonal allergens compared to the SPT in cases positive for HDM allergens.