Oral and sublingual immunotherapy: general aspects and critical considerations

Local routes for immunotherapy (IT) such as oral (OIT) and sublingual (SLIT) have the primary aim of avoiding or minimizing the risk of adverse events and of improving the compliance of the patients with IT itself. About the possible mechanisms of action, only few information are available since local IT has been deeply studied only in the last ten years. The current data about pharmacokinetics are controversial and not conclusive, since they are mostly derived from animal models. However, very recent studies have demonstrated that the sublingual/swallow modality is the most promising way of mucosal immunotherapy. Thus, SLIT could be shown to lead to systemic immunological effects and to a decreased responsiveness of target organs. Furthermore, no severe adverse events were reported in the SLIT-studies. Some studies indicate that SLIT is as effective as subcutaneous IT, whilst OIT is not recommended for the clinical practice. SLIT would appear particularly suitable for pediatric patients. Administration schedules include a build-up phase and a maintenance phase which can be administered either preseasonally or continuously, and rush schedules for preseasonal IT are also available. Furthermore, SLIT reduces time and money expenses usually required by SIT since it is self-administered.