Subcutaneous Versus Mucosal (Intranasal) Allergen-Specific Rush Immunotherapy in Experimental Feline Asthma
Allergen specific immunotherapy addresses a dysregulated (Th2) immune response to aeroallergens. Previously, subcutaneous rush immunotherapy (SC RIT) was shown to dampen eosinophilic airway inflammation in experimental feline asthma; however, side effects were noted. In humans, mucosal immunotherapy has an improved safety and efficacy profile compared with SC RIT. In this study, we hypothesized that IN RIT would be as efficacious as and safer than SC RIT.
Twelve cats were sensitized and challenged with bermuda grass allergen (BGA) and randomly received SC or IN RIT. RIT was given over 2 days (doses of 20-200mcg of BGA) followed by 200mcg BGA weekly as maintenance. Adverse reactions were recorded. Bronchoalveolar lavage fluid (BALF) % eosinophils, and BALF IL-4 and IFN-g concentrations were measured before RIT (Day 1) and at months 1, 3 and 6 (M1, M3, M6).
Twelve adverse reactions were seen with SC RIT vs 6 with IN RIT; however, all were mild and self-limiting. BALF % eosinophils decreased after RIT in both groups (mean±SEM, SC RIT D1 62±12, M6 9±4; IN RIT D1 54±9, M6 14±6). The BALF IL-4:IFNg ratio decreased in both groups (mean±SEM, SC RIT D1 1.6±.4, M6 1.2±.3; IN RIT D1 2.4±.2, M6 1.0±.2).
Both protocols dampened airway eosinophilia and altered the Th2:Th1 cytokine profile locally; IN RIT had fewer adverse events. Either could be considered for treating allergic asthma.