Methods: We retrospectively analyzed 51 HDM-sensitized children aged 5 to 16 years diagnosed with allergic rhinitis and/or asthma, following 36 months of SIT. We also collected data from a contemporary control cohort of 50 patients administered routine medications for HDM allergy. . In the test cases, we recorded the sIgE and sIgG4 levels against the whole allergen of HDM (Der p), Der p 1 and Der p 2 at baseline and at 6, 12, 24 and 36 months of SIT.
Results: The serum sIgE response increased up to 6 months of SIT, but subsequently declined. At 36 months, the anti-Der p 1 and anti-Der p 2 sIgEs plummeted below the baseline. During SIT, the increased serum sIgG4 response was the greatest against Der p, followed by Der p 1 and Der p 2. The decline in sIgE/sIgG4 ratio for Der 1 was higher than for the other allergensmaximum decline. Compared with older children, children aged 5 to 8 manifested a clearer sIgG4 response, especially against Der p 1 and Der p 2 versus Der p.
Conclusions: SIT for HDM stimulated an early sIgE and sIgG4 response against HDM allergens. with a progressive decline in the ratio of sIgE/sIgG4, especially against Der p 1. Younger children may manifest a more rapid response to SIT than older ones.