A double-blind study of hyposensitization with an alginate-conjugated extract of Dermatophagoides pteronyssinus (Conjuvac®) in patients with perennial rhinitis. II. Immunological aspects

In a 2-year double-blind placebo controlled study an immunological evaluation was carried out on 33 patients (15 males, 18 females, mean age 29.2 years) with mite-induced perennial rhinitis who were submitted to specific immunotherapy (IT) with an alginate-conjugated extract of D. pteronyssinus. The behaviour of IgE, IgG, IgG₁ and IgG₄ antibodies specific to D. pteronyssinus and its major allergen Der p₁ was characterized by assessment of their changes in serum, and changes in IgG in nasal secretions during the treatment. The placebo-treated patients did not show any significant variation in the levels of specific antibodies, while in the actively treated patients we found: a statistically significant decrease (P <0.005) of specific IgE, a statistically significant increase of specific IgG (P <0.005), IgG₁ (P <0.005) and IgG₄ (P <0.005) in serum and a statistically significant increase (P <0.001) of specific IgG in nasal secretions. The IgG response showed an early relative predominance of the IgG₁ subclass and a late absolute predominance of IgG₄ subclass, that confirmed the model of IgG₄ restriction in prolonged allergen stimulation. No correlation was found between immunological and clinical data.