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.