Immune system network in allergic diseases during sublingual immunotherapy: The role of oral mucosal tissue

Abstract

Specific sublingual immunotherapy (SLIT) represents an approach currently available to redirect inappropriate immune response in atopic patients. Since oral mucosal tissue displays high affinity for allergens, it is conceivable that the sublingual administration route might induce immunological tolerance towards allergens involving cells and mediators specific of oral and intestinal mucosa. The presence in oral mucosa of dendritic cells (DCs) which express the high-affinity receptor for immunoglobulin (Ig)E (FceRI) seems to suggest that the generation of T regulatory cells in periphery is orchestrated by a particular subset of DCs. It seems that repeated stimulation of naïve CD4 T cells with allogenic immature DCs induce Tr1 cell maturation. Nevertheless, other cells are involved in this process, such as Toll Like Receptors (TLR), Major Histocompatibility Complex I and II (MHC I and II) and costimulatory molecules, such as CD40, CD 80/B7.1 and CD 86/B7.2. An increase of serum IgG4 and IgA, a reduced number of inflammatory cells infiltrating target organs, as well as a reduction of eosinophilic cationic protein and a T cell suppression in the peripheral blood also occur with SLIT. All these molecules orchestrate the immune network within the regional immune system, recreating a favourable environment for the induction of tolerance operated by SLIT.

Keywords

Oral mucosa - dendritic cells - Sublingual immunotherapy (SLIT) - Immunological tolerance