Introduction

Allergic diseases, including respiratory (allergic rhinitis and asthma) and food allergy (FA), and drug hypersensitivity reactions (DHRs), have shown an important increase in their prevalence over the last decades.1-4 Severe rhinitis and asthma, and potentially fatal anaphylaxis due to food and drug intake are a burden because of their high impact in life-quality and cost for the health system.5-7 Moreover, there is a great heterogeneity of clinical symptoms, mechanisms, and specific gaps regarding comorbidities, making diagnosis complex, with low sensitivity or specificity, and treatments with low efficacy or no achievement of disease control.8-11
Regarding the diagnostic approaches, the main goal is improving sensitivity and specificity to diminish the false negative results, which can be critical in severe reactions, and the false allergic labelling of the patients, which is a main problem in DHRs.12-16 A precise diagnosis will improve the management of the patients by applying accurate treatments. There is a need for new validated in vitro tests since, despite the existence of several approaches, they pose limitations regarding the real clinical relevance of positive results in cases of rhinitis, asthma, and FA, and their low sensitivity in DHRs.17-23
Concerning treatment, although the first line is the allergen/drug avoidance, this is not always possible, especially FA, in which accidental ingestion could happen due to the ubiquity of allergens and hidden sources. Therefore, other managements that influence the aetiology of the disease, as allergen specific immunotherapy (AIT), must be applied. Although different formulas have been commercialised with beneficial results in inducing tolerance to the patients24-27, AIT does not completely reduce the risk of severe reactions and shows a lack of homogeneity between batches and difficulties on the obtainment of the natural allergenic extract.28,29 Thus, it has been suggested the need of improving the efficacy of AIT using different approaches.30
During the last years, applications of nanotechnology for diagnosis and treatment in the field of immunology and allergy have increased and are being referred as nanomedicine.31 We aim to present an overview of different nanostructures used in biomedicine and their potential suitability for in vitro diagnostic tests as well as for their role in novel immunotherapy.