Sublingual immunotherapy (SLIT) – indications, mechanism, and efficacy

SLIT (sublingual immunotherapy,) induces allergen-specific immune tolerance by sublingual administration of a gradually increasing dose of an allergen. The mechanism of SLIT is comparable to those during SCIT (subcutaneous immunotherapy), with the exception of local oral dendritic cells, pre-programmed to elicit tolerance. In the SLIT dose, to achieve the same efficacy as in SCIT, it should be 50–100 times higher with better safety profile. The highest quality evidence supporting the efficacy of SLIT lasting 1 – 3 years has been provided by the large scale double-blind, placebo-controlled (DBPC) trials for grass pollen extracts, both in children and adults with allergic rhinitis. Current indications for SLIT are allergic rhinitis (and conjunctivitis) in both children and adults sensitized to pollen allergens (trees, grass, Parietaria), house dust mites (Dermatophagoides pteronyssinus, Dermatophagoides farinae), cat fur, as well as mild to moderate controlled atopic asthma in children sensitized to house dust mites. There are positive findings for both asthma and new sensitization prevention. Severe adverse events, including anaphylaxis, are very rare, and no fatalities have been reported. Local adverse reactions develop in up to 70 – 80% of patients. Risk factors for SLIT adverse events have not been clearly identified. Risk factors of non-adherence to treatment might be dependent on the patient, disease treatment, physician-patient relationship, and variables in the health care system organization.