Purpose of review: To summarize novel insights into the immunological mechanisms of sublingual immunotherapy (SLIT). Within the recent decades, several alternative noninvasive allergen application strategies have been investigated in allergen-specific immunotherapy (AIT), of which intra-oral allergen application to sublingual mucosa has been proven to be well tolerated and effective.
Recent findings: To date, SLIT is widely accepted by most allergists as an alternative option to conventional subcutaneous immunotherapy (SCIT). Although detailed immunological mechanisms remain to be elucidated, much scientific effort has been made to shed some light on local and systemic immunological responses to SLIT in mice as well as humans. Only a few studies focused on the detailed mechanisms following allergen application to the oral mucosa as part of the sophisticated mucosal immunological network. Within this network, the pro-tolerogenic properties of local antigen-presenting cells (APCs) such as dendritic cells – which are able to enforce tolerogenic mechanisms and to induce T-cell immune responses – play a central role. Further on, basic research focused not only on the immune response in nasal and bronchial mucosa but also on the systemic T-cell immune response.
Summary: Thus, much exiting data have been published providing a better understanding of immunological features of SLIT but far more investigations are necessary to uncover further exciting details on the key mechanisms of SLIT.