Variation of the skin end-point in patients treated with sublingual specific immunotherapy

The reduction in skin reactivity in sensitized subjects is a common finding after injective specific immunotherapy. Few data are, on the contrary, available for sublingual immunotherapy. We assessed the skin reactivity by the end-point titration method in 90 monosensitized subjects (age range 3-50; mean age 19.63) at the baseline and for four consecutive years during the SLIT treatment with two different maintenance regimens. The yearly duration of drug intake was monitored throughout the observation period. Age and skin reactivity to histamine (p < 0.0001; r = 0.871), and age and skin prick end-point (p < 0.0001; r = 0.523) turned out to be statistically positively correlated at baseline. No correlation was on the contrary found between age and the ratio allergen wheal/histamine wheal (p = 0.857; r = -0.019). After 4 years all patients showed at least a significant 4-fold decrease of the skin end-point, whereas 46/90 (51.1%) showed a 16-fold decrease and 29/90 (32.2%) a 64-fold decrease (p < 0.001 in all cases). At the end of the SLIT treatment, 21/90 patients (23.3%) were not using any drug, whereas 16/16 (100%) had given up the use of eye drops, and 34/35 (97%) had given up the use of bronchodilators and bronchial steroids (p < 0.001). After SLIT, 52/90 patients showed a reduction by at least 50% of the yearly duration of drug intake (p < 0.0001). An apparent relationship between the progressively decreasing rate of use of drugs and the decrease in skin reactivity was found, but it did not reach the point of statistical significance (p = 0.081). Patients treated with the daily allergen administration schedule, in spite of a lower cumulative dosage, showed a significantly greater decrease in skin reactivity (p < 0.001) and a higher rate of both no use of any drug (p = 0.013) and of at least a 50% reduction of the yearly duration of drug intake (p = 0.001) as compared to patients treated with three allergen administrations per week.