The Response To Sublingual Immunotherapy With Grass Pollen Extract Administered As A Single Extract Or As Part Of A Multi-Allergen Extract In Patients With Seasonal Allergic Rhinitis Caused By Grass Pollen

RATIONALE: The purpose of this study was to examine whether the efficacy of sublingual immunotherapy (SLIT) with standardized timothy extract alone was reduced by combination with other allergen extracts. METHODS: A single-center, randomized, double-blind, placebo-controlled trial with SLIT was conducted. After an observational grass season, SLIT was administered to 54 patients for 10 months. The subjects were randomized to 1 of 3 treatment arms: placebo, timothy extract (20 mcg Phl p 5 daily) as monotherapy (TM), or the same dose of timothy extract plus 9 additional allergen extracts (multi-allergen therapy, MAT). Compliance was >80%. Symptom and medication scores, titrated nasal challenges (NC), titrated skin prick tests (tSPT), specific IgE and IgG4 to timothy were measured. PBMCs were stimulated with timothy allergen to measure secreted cytokines. RESULTS: There was no significant difference in medication or symptom scores in either treatment groups compared to placebo. There was a significant improvement in the TM NC results verses placebo (p = 0.03). There were also significant improvements in tSPT in the TM group (p = 0.001) and MAT (p = 0.037) compared to placebo but not between TM and MAT. IFN- γ levels significantly decreased in the TM verses placebo groups (p = 0.02). There were significantly more adverse events in the active groups, TM (84%, p < 0.0001) and MAT (65%, p = 0.0003), compared to placebo (6%). CONCLUSIONS: Although there were no significant outcome differences between TM and MAT, trends for greater improvement in several parameters with TM suggest a reduction in SLIT efficacy with multi-allergen treatment.