Editorial: Allergen cross-reactivity - a challenge in daily practice

Reina et al. [8] in their original research explored cross-sensitization and crossreactivity between the allergens of house dust mites (HDM) and cockroaches in the tropical environment. Their results identify house dust mite allergens as primary sensitizers in inhabitants of a tropical environment of the city of Cartagena, Colombia. In addition, these authors have explored cross-sensitizations between HDM allergenic proteins and those of cockroaches, shrimp, and Anisakis simplex, concluding that cockroach sensitization should be considered as important hallmark of potential cross-reactivity with allergens coming from crustaceans, and, therefore, warrant more thorough approach during clinical assessment.In the second original paper in this Research Topic, Maskey et al. [9] approach, using the mouse model, an important clinical problem of cross-reactivity between peanut and tree nut allergens. In an attempt to study this potential cross-sensitization, an intraperitoneal sensitization (priming) with a mix of peanut, tree nuts and cashew allergens was performed, and subsequently, specific IgE levels against priming and potentially cross-reactive allergens were measured. Broad cross-reactivity was ascertained, as assessed through specific IgE levels, additionally confirmed by experimental anaphylaxis. Development of this model can be considered a valuable contribution to the advancement of the research on nut cross-reactivity. This Research Topic also contains 2 review papers, which present topics valuable from both basic and clinical points of view. Berghea et al. [10], in their narrative review, describe the wide spectrum of allergic sensitization to spices and herbs, with special focus on the pediatric population. Both IgE-dependent and non-IgE-dependent mechanisms have been highlighted, and the problem of cross-reactivity with pollen allergens was indicated. In the second review contained in this Topic, O'Malley et al. [11] describe calcium-binding proteins (CBPs), an important yet often neglected family of allergenic proteins that, on a standard basis, is not considered a potential cause of cross-reactive reactions. Calcium-binding proteins, due to their heterogeneity, crossreactivity, and presence in multiple allergenic sources, are difficult to avoid. The fact that CBPs can sensitize both through inhalation and ingestion makes them even more worth consideration in the course of a diagnostic approach in an allergy practice.Finally, Schreiber and Guillet [12] presented a description of a rare case of severe IgEmediated hypersensitivity to carboxymethylcellulose (CMC) following an intraarticular knee injection with triamcinolone acetonide. A thorough diagnostic approach allowed them to diagnose a patient with IgE-mediated, and clinically relevant, hypersensitivity to CMC, yet with confirmed lack of sensitization to potentially cross-reactive cellulose derivatives. Reports describing rare cases of IgEmediated generalized reactions to less obvious agents, such as excipients exemplified by CMC, largely contribute to expanding our knowledge and increase our vigilance and critical thinking. Such an approach is irreplaceable when aiming at highest levels of diagnostic insightfulness and thoroughness.