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

Contact dermatitis caused by preservatives.

Liver toxicity as a limiting factor to the increasing use of immune checkpoint inhibitors.

Ciprofloxacin (CPFX) is a widely used fluoroquinolone antibiotic, inducing cutaneous adverse drug reactions in about 1 to 2% of the treated patients. Conclusive diagnosis of drug allergy, however, still remains a major problem in daily clinical practice. Here, we present 2 patients with drug allergy to CPFX. In both cases the clinical suspicion for CPFX as the causative agent was confirmed in vitro by means of the lymphocyte transformation test, whereas epicutaneous patch tests remained negative. In vivo, a small percentage of the drug is biotransformed to the three major metabolites desethylene-, sulfo- and oxociprofloxacin. Though structurally closely related to their mother compound, these metabolites failed to induce in vitro lymphocyte proliferation in both patients. On the other hand, in vitro crossreactivity to ofloxacin, another fluorinated quinolone, could be demonstrated, which to our knowledge has not previously been reported.

IntroductionHouse dust mite (HDM) allergens are major triggers of IgE-mediated asthma in tropical regions, yet the role of cockroach allergens and their cross-reactivity with HDM remains unclear. Cross-reactivity among invertebrate allergens is a common challenge in daily practice, especially to define primary sensitizers and reactions of clinical relevance. Multiplexed arrays in molecular allergology constitute a useful tool for better detection and interpretation of cross-reactions.MethodsWe assessed specific IgE levels and skin prick test reactivity to the American cockroach and HDM allergens in cohorts of allergic and asthmatic patients from Cartagena, Colombia, using ImmunoCAP™, skin testing, and multiplex molecular allergology (ALEX2).ResultsCockroach sensitization was present in 29%–40% of patients but elicited significantly lower IgE responses and smaller skin test wheals compared with HDM. Most cockroach-sensitized individuals were cosensitized to HDM, with limited recognition of cockroach molecular components. Mean specific IgE levels to cockroach were 2.1 kU/L ranging from 0.1 to 25.8 kU/L. The majority of patients had IgE levels in Class 1 (0.35–0.70 kU/L) or Class 2 (0.70–3.5 kU/L). In the ALEX2 array, most cockroach-sensitized patients (by skin tests) did not recognize the Periplaneta americana extract (Per a) or other cockroach allergens in the array, and instead they recognized HDM allergens and the extracts of crustaceans and mollusks. Only one patient recognized the Per a extract, cockroach tropomyosin (Per a 7), and tropomyosins in HDM (Blo t 10, Der p 10), shrimp (Pen m 1), and Anisakis simplex (Ani s 3) together with other allergens in crustaceans and mollusks. Interestingly, IgE reactivity to cross-reactive allergens like arginine kinase, myosin light chain, and sarcoplasmic calcium-binding protein was not detected. Cockroach sensitization was not associated with worsened asthma control or lung function but correlated with higher shrimp-specific IgE in patients reporting shellfish allergy.DiscussionHDM allergens induce stronger IgE responses than cockroach in this tropical population, indicating HDM as the primary sensitizer. Cockroach sensitization often reflects cross-reactivity and requires careful clinical evaluation to determine its relevance.