Reduction of Substance P in Nasal Lavage Fluid after Allergen Challenge of Mugwort Allergic Patients during Allergen Immunotherapy

Abstract

Allergen specific immunotherapy (ASIT) may impact neuropeptides released into nasal lavage fluid (NLF) including substance P (SP). 15 subjects (8 females and 7 males) mean age 33.0 ± 7.8 years with symptoms during the previous mugwort pollen season were treated with ASIT as pre-seasonal weekly injections of a mugwort pollen allergoid (Allergovit) for 3 years. All had both positive skin prick tests to mugwort pollen allergen and elevated specific IgE to mugwort pollen (Phadia). The control group consisted of 9 untreated subjects. Nasal mugwort allergen challenge with subsequent lavage performed 15 minutes post-challenge was done by the method of Naclerio. The concentration of SP in NLF was determined by RIA (Incstar, USA). Nasal symptoms during the pollen seasons were recorded. Reduction of symptom scores occurred during the three years of ASIT. Levels of SP in NLF after nasal mugwort challenge in both groups prior to therapy were similar: ASIT group - SP 55.1 ± 15.5 pg/ml versus control group- 54.3 ± 10.1 pg/ml. SP levels in NLF 15 minutes after mugwort allergen challenge were significantly less after 1 year of ASIT versus controls (47.4 ± 14.0 pg/ml versus 53.6 ± 6.8 pg/l) with modest further decrease in SP levels in post-challenge NLF after 2 years of ASIT (42.2 ± 9.6 pg/ml versus 51.2 ± 9.2 pg/ml) and 3 years of ASIT (41.6 ± 18.3 pg/ml versus 51.8 ± 7.6 pg/ml). SP may play a role in nasal allergic responses to mugwort pollen. Decreased release of SP upon nasal allergen challenge occurs with each year of ASIT suggesting that ASIT reduces allergen-induced SP release.