Rationale: Nasal allergen provocations may be useful in investigating the pathophysiology
of allergic rhinitis and effects of treatments.
Objective: To use grass pollen nasal allergen challenge (NAC) to investigate the
effects of allergen immunotherapy in a cross-sectional study.
Methods: We studied nasal and cutaneous responses in untreated subjects with
seasonal grass-pollen allergic rhinitis (n = 14) compared with immunotherapytreated
allergics (n = 14), plus a nonatopic control group (n = 14). Volunteers
underwent a standardized NAC with 2000 biological units of timothy grass allergen
(equivalent to 1.3 lg major allergen, Phl p5). Nasal fluid was collected and
analysed by ImmunoCAP and multiplex assays. Clinical response was assessed by
symptom scores and peak nasal inspiratory flow (PNIF). Cutaneous response was
measured by intradermal allergen injection. Retrospective seasonal symptom
questionnaires were also completed.
Results: Immunotherapy-treated patients had lower symptom scores (P = 0.04)
and higher PNIF (P = 0.02) after challenge than untreated allergics. They had
reduced early (P = 0.0007) and late (P < 0.0001) skin responses, and lower retrospective
seasonal symptom scores (P < 0.0001). Compared to untreated allergics,
immunotherapy-treated patients had reduced nasal fluid concentrations of IL-4,
IL-9 and eotaxin (all P < 0.05, 8 h level and/or area under the curve comparison),
and trends for reduced IL-13 (P = 0.07, area under the curve) and earlyphase
tryptase levels (P = 0.06).
Conclusions: Nasal allergen challenge is sensitive in the detection of clinical and
biological effects of allergen immunotherapy and may be a useful surrogate marker
of treatment efficacy in future studies.