Differential Induction of Allergen-specific IgA Responses following Timothy Grass Subcutaneous and Sublingual Immunotherapy.

Abstract Introduction There is no detailed comparison of allergen-specific immunoglobulin responses following sublingual (SLIT) and subcutaneous (SCIT) immunotherapy. Objective To compare nasal and systemic Timothy grass pollen (TGP)-specific antibody responses during two years of SCIT and SLIT and one year after treatment discontinuation in a double-blind, double-dummy, placebo-controlled trial. Methods Nasal fluid and serum were obtained yearly (per-protocol population, n=84). TGP-specific IgA1, IgA2, IgG4, IgG and IgE were measured in nasal fluids by ELISA. TGP-specific IgA1, IgA2 and Phl p1, 2, 4, 5b, 6, 7, 11 and 12 IgE and IgG4 were measured in sera by ELISA and ImmunoCAP, respectively. Results At years 2 and 3, TGP-IgA1/2 in nasal fluid were elevated in SLIT compared to SCIT (4.2 and 3.0-fold for IgA1, 2.0 and 1.8-fold for IgA2, respectively; all P Conclusion The observed induction of IgA1/2 in SLIT and IgG4 in SCIT suggest key differences in the mechanisms of action.