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In the last few decades, glucocorticoids have received increasing attention for their capability of provoking systemic hypersensitivity reactions, when administered orally, parenterally, or intralesionally, as well as allergic skin and mucosal symptoms, when applied locally to the skin in patients with contact dermatitis or to the mucosa in patients with asthma and/or rhinitis. However, because of their anti-inflammatory and immunosuppressive properties, glucocorticoids are often not suspected of such hypersensitivity reactions. In addition, because glucocorticoids retain their anti-inflammatory potential, even if they act as sensitizers, the signs and symptoms of allergic reactions are not always obvious, particularly when they overlap with those caused by the very diseases glucocorticoids are used to treat. Moreover, interpretation of diagnostic tests, specifically that of patch-test reactions, can be difficult. In this review, particular attention is addressed to the problem of allergenic cross-reactivity among topical and systemic glucocorticoids. We also look at the clinical and practical aspects of both cell-mediated and IgE-mediated hypersensitivity reactions to glucocorticoids and their consequences on anti-inflammatory therapeutic choices.

Temporary henna-based tattoos, particularly popular among western tourists holidaying in exotic places, can expose to the risk to develop allergic reactions. Although hypersensitivity to henna is extremely rare, para-phenylenediamine, which is sometimes added to henna to obtain a dark, blackish color, is a frequent contact sensitizer. The purpose of this article is to review the literature about allergic reactions to temporary henna tattoos and outline the causes, clinical aspects and complications of this practice that should not be regarded as innocuous and risk-free.

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The diagnosis of food allergy, as assessed by skin tests or in vitro tests with allergen extracts, has insufficient diagnostic performance and needs to be confirmed by food challenges. However, the availability of molecular allergens (recombinant or highly purified) for laboratory methods has profoundly changed the diagnostic approach to food allergy. In fact, the allergy diagnosis conducted at the molecular level, which is defined internationally as component resolved diagnosis (CRD), allows to characterize more precisely the sensitization profile of the individual patient, distinguishing the sensitizations to allergens that are strongly associated with a given source (genuine sensitizers) from those to molecules that are common to many sources (panallergens) or cross-react with other components from the same family or from other families. This review provides an update on the allergen molecules from foods, including plant foods and animal foods, and on the techniques to detect them, by means of a single reagent (singleplex) or an array of molecules tested at the same time (multiplex). Such testing offers detailed information on the sensitization profile of patients and enables the physician to suitably manage their allergy. Moreover, identifying the real causative allergens will be crucial when allergen immunotherapy for food allergy will be introduced in the near future. We also address patents concerning food allergens in this review.

Glucocorticoids (GCs) represent the most effective treatment for autoimmune and allergic diseases, even if collateral effects are not rare, especially endocrine and immunosuppressive manifestations. Moreover, these drugs can develop adverse immunological reactions of I, III or IV type. Though immediate adverse reactions caused by systemic therapy with GCs are not very frequent, the possible beginning of anaphylactic and pseudo-anaphylactic manifestations in patients undergoing therapy with these drugs has to be considered. It has been observed that immediate adverse reactions usually are happened in asthmatic patients and in patients obliged to assume GCs again and again because of their pathology (e.g, kidney transplant). Other risk factors resulted to be female sex and hypersensibility to acetylsalicylic acid (ASA). Both in the cases of pseudo-allergic and allergic reactions, the pharmacological principle is hardly the responsible agent for the reaction; instead the excipients in drugs are often implicated (succinate salt, sulphites and carboxy-methyl-cellulose). It is possible that the IgE-response is highly specific for a fixed GC molecule as well depending on the way of administration and its salification. Moreover, it has been hypothesized that in patients with a first type allergic reaction to GCs there is a fourth type, sensitization to GCs, which is not usually diagnosed and even comes before IgE sensitization. Third type hypersensibility reactions may occur, too. Since GCs are large-scale drugs, also in emergency medicine and reanimation, allergic sensitization towards them, although infrequent, gives many interventionist problems. In the light of this feature, it seems of crucial importance to verify the tolerance toward other GC molecules. And in particular, it has been noted that patients presenting immediate reactions to hydrocortisone (HC) and methylprednisolone (MP) could tolerate prednisone and prednisolone per os and second-generation GCs, such as desamathazone and betamethazone. Nevertheless, second-generation GCs must not be considered safe; in fact, the beginning of allergic manifestations has been pointed out even towards them.

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