Specific immunotherapy for perennial allergic rhinitis

The objectives of this double-blind, randomised, placebo-controlled study (DBPC) were to assess the efficacy of SIT with standardised cat dander extract (Alutard-SQ, ALK-Abello), using objective endpoints and simulated 'natural' exposure to cats. 28 adult patients suffering form moderate to severe perennial allergic rhinoconjuctivitis and asthma induced by the cat allergy were randomised to active or placebo treatment. When assessed after reaching the maintenance dose, the actively-treated group showed marked reduction in symptom scores and peak flow rate and FEV1 falls during and after exposure to cats in a domestic living room occupied by three cats, together with parallel improvements in conjunctival provocation threshold and skin sensitivity (P<0.001 each). Placebo values were unchanged. Interestingly, the active treatment group also showed a significant reduction (P<0.05) in cutaneous sensitivity to D. pteronyssinus. No significant adverse reactions were encountered. Thus, SIT seems to be an effective treatment for cat allergy and may be considered as a valid option in selected cases. Furthermore, cat SIT may have additional benefits on sensitivity to unrelated allergens.In a parallel study, 28 adult patients with moderate to severe perennial rhinitis and mild asthma attributed to HDM sensitivity were enrolled for SIT in a randomised DBPC trial. The active group received immunotherapy using a standardised D. pteronyssinus extract (Alutard-SQ, ALK-Abello). When assessed after one year of treatment, the treatment group showed a 58% reduction in total diary card symptoms (P=0.002) and a 20% decrease in concomitant drug requirement. In particular, nasal symptom and drug scores reduced significantly (P<0.05 each) by 70% and 60% respectively, but asthma symptom and drug scores were both unchanged (P=NS). The placebo group had a 32% waning in symptom score (P=NS) and no change in drug usage. Cutaneous LPR to cat allergen was reduced by 35% (P=0.043) in the HDM actively-treated group compared to placebo control.