Allergen-derived T cell peptides in immunotherapy

The incidence of allergic diseases has continued to rise during the last 30 years. A combination of genetic and environmental factors is likely to be responsible for the increased prevalence of both allergic and autoimmune diseases. Whilst the majority of approaches towards treatment are palliative, specific allergen immunotherapy (SIT) is an approach that has been proven to be efficacious and disease-modifying. However, as a result of interaction between allergen-specific IgE and conformational B cell epitopes on the surface of the allergen molecule, SIT is associated with adverse reactions during treatment. One strategy developed to reduce IgE-mediated adverse events whilst maintaining clinical efficacy has been to treat subjects with short peptide sequences corresponding to T cell epitopes of the allergen. The size and the monomeric nature of peptides have allowed relatively large doses of antigen to be delivered in soluble form. Treatment with peptides has been shown to improve clinical surrogate measurements of disease, to modify the immune response to allergen and to improve patients’ perception of disease. This review will summarise results achieved in recent years with peptide immunotherapy and discuss the mechanisms that may be responsible for efficacy.