Sublingual grass pollen immunotherapy is associated with increases in sublingual Foxp3‐expressing cells and elevated allergen‐specific immunoglobulin G4, immunoglobulin A and serum inhibitory activity for immunoglobulin E‐facilitated allergen binding to B cells

Abstract

Summary: Background The mechanisms of sublingual immunotherapy (SLIT) are less well understood than those of subcutaneous immunotherapy (SCIT). Objectives To determine the effects of grass‐pollen SLIT on oral mucosal immune cells, local regulatory cytokines, serum allergen‐specific antibody subclasses and B cell IgE‐facilitated allergen binding (IgE‐FAB). Methods Biopsies from the sublingual mucosa of up to 14 SLIT‐treated atopics, nine placebo‐treated atopics and eight normal controls were examined for myeloid dendritic cells (mDCs) (CD1c), plasmacytoid dendritic cells (CD303), mast cells (AA1), T cells (CD3) and Foxp3 using immunofluorescence microscopy. IL‐10 and TGF‐β mRNA expression were identified by in situ hybridization. Allergen‐specific IgG and IgA subclasses and serum inhibitory activity for binding of allergen‐IgE complexes to B cells (IgE‐FAB) were measured before, during and on the completion of SLIT. Results Foxp3 + cells were increased in the oral epithelium of SLIT‐ vs. placebo‐treated atopics ( P =0.04). Greater numbers of subepithelial mDCs were present in placebo‐treated, but not in SLIT‐treated, atopics compared with normal controls ( P =0.05). There were fewer subepithelial mast cells and greater epithelial T cells in SLIT‐ compared with placebo‐treated atopics ( P =0.1 for both). IgG 1 and IgG 4 were increased following SLIT ( P <0.001). Peak seasonal IgA 1 and IgA 2 were increased during SLIT ( P <0.05). There was a time‐dependent increase in serum inhibitory activity for IgE‐FAB in SLIT‐treated atopics. Conclusions SLIT with grass pollen extract is associated with increased Foxp3 + cells in the sublingual epithelium and systemic humoral changes as observed previously for SCIT. Cite this as : G. W. Scadding, M. H. Shamji, M. R. Jacobson, D. I. Lee, D. Wilson, M. T. Lima, L. Pitkin, C. Pilette, K. Nouri‐Aria and S. R. Durham, Clinical & Experimental Allergy , 2010 (40) 598–606.