A recent molecular analysis reveals that many patients labelled as cockroach-allergic may actually be reacting to shared proteins found across mites, seafood and insects, highlighting the need for more precise allergy diagnostics, reports News Medical.
The study, led by scientists from the Medical University of Lodz, Poland, and published in Scientific Reports, found that allergic reactivity to cockroaches may reflect sensitisation to a broader spectrum of cross-reactive allergens in patients with perennial allergic rhinitis (PAR).
Cockroach allergy often coincides with sensitivities to other arthropods, seafood, dust mites, and certain wasp species. Patterns of overlapping antigen responses vary by cockroach species, revealing distinct species-specific cross-reactivity patterns among allergens, and these findings may improve personalised allergy profiling and support more targeted management strategies for patients with allergic rhinitis (AR).
Cross-reactivity, in which the immune system responds to structurally similar allergens, plays a key role in allergic diseases and can worsen symptoms. Cockroach sensitisation is a major trigger of AR and asthma and often occurs alongside reactions to house dust mites, seafood, and other indoor allergens.
Despite its clinical importance, research gaps remain regarding species-specific molecular sensitisation patterns. Polysensitisation is rising and affects more than 80% of allergic rhinitis patients, often leading to more severe symptoms.
Understanding these patterns is essential for improving allergen-specific immunotherapy and guiding personalised management strategies, particularly for children and high-risk populations.
Molecular sensitisation patterns
The researchers in Poland investigated molecular patterns of cockroach sensitisation in 250 patients with PAR, with a mean age of 32 (158 males and 92 females). All participants were referred to an allergy clinic and underwent skin prick testing (SPT) for common airborne allergens.
Tested allergens included house dust mites (Dermatophagoides pteronyssinus and D. farinae), cockroach (Blattella germanica), birch, mugwort, grass, dog, cat, and Alternaria. Results showed that 48 of them (19%) tested positive for cockroach extract and were selected for further molecular analysis.
Two participants declined blood sampling. The remaining 46 patients underwent the ALEX2 multiplex diagnostic test, an enzyme-linked immunosorbent assay (ELISA)–based platform that simultaneously measures specific immunoglobulin E (sIgE) for 295 allergens. Values ≥0.3 kU/L were considered positive.
Researchers evaluated sensitisation to B. germanica-specific allergens and related cross-reactive molecules from Periplaneta americana. B. germanica-specific allergens included Bla g 1, Bla g 2, Bla g 4, Bla g 5, and Bla g 9.
Additional analyses assessed sensitisation to a wide range of potential cross-reactive sources, including edible insects, mites, Hymenoptera venom, and seafood.
The researchers first analysed correlations between SPT results and ALEX2 findings. They then examined molecular sensitisation patterns with a focus on cross-reactivity between cockroach allergens and other arthropod, environmental, and seafood allergens.
Cross-reactive proteins play huge role
The study showed that cross-reactivity plays a major role in the Polish PAR patients allergic to cockroaches. Only a small proportion displayed elevated IgE responses to cockroach-specific allergens, while most reacted primarily to cross-reactive proteins such as tropomyosins and arginine kinases.
Per a 7 from P. americana strongly correlated with tropomyosins from shrimp, storage mites, and house dust mites, highlighting the role of cross-reactive proteins in complex allergic responses.
The researchers also detected a high correlation between Bla g 5 (glutathione S-transferase) and Der p 11 (paramyosin), reflecting shared structural epitopes across cockroach, mite, and other invertebrate allergens.
Only two patients exhibited IgE sensitisation to cockroach-specific allergens, showing elevated IgE levels to Bla g 1 and Bla g 4. Most individuals were sensitised mainly to cross-reactive allergens.
Some patients reacted to arthropod extracts despite lacking detectable IgE to tested cockroach-specific or cross-reactive molecular allergens. This suggests the presence of additional unidentified cross-reactive allergenic molecules in arthropod extracts.
Sensitisation patterns also extended to edible insects like locusts, crickets, and mealworms, as well as storage mites, dust mites, seafood, and wasp species. Profiles varied depending on cockroach species.
Further analyses revealed moderate correlations between B. germanica and house dust mite allergens.
Strong correlations were also observed among dog and cat allergens, as well as among house dust mite allergens.
Species-specific differences were evident. Per a 7 correlated with edible insects, storage mites, and seafood allergens, while Bla g 9 showed broader associations with dust allergens and wasp species.
These findings indicate that tropomyosin and related proteins drive extensive cross-reactivity among invertebrate allergens, explaining the complex sensitisation patterns observed in cockroach-allergic patients.
Molecular diagnostics could improve diagnosis
The study shows that cockroach sensitisation in PAR patients frequently coincides with sensitisation to multiple cross-reactive allergens, including edible insects, seafood, storage mites, dust mites, and wasp species.
Importantly, diagnostic testing based solely on cockroach extracts may over-estimate true cockroach sensitisation because extract-based tests can detect IgE responses to cross-reactive molecules rather than cockroach-specific allergens.
Component-resolved diagnostics can help distinguish genuine sensitisation from cross-reactive responses. This approach may support more precise allergen-specific immunotherapy (ASIT) and improve patient management.
The findings have important clinical implications for allergy diagnosis and treatment by helping clinicians identify true sensitisation patterns and anticipate cross-reactive triggers.
Future studies should include larger, more diverse populations while accounting for biological, environmental, socioeconomic, and genetic factors to improve understanding of cross-reactivity and optimise management strategies for patients with allergic rhinitis.
Study details
Cockroach sensitisation and its hidden links to mite and food allergens
Marharyta Sobczak, Patrycja Kitlas, Rafał Pawliczak & Krzysztof Kowal.
Published in Nature Scientific Reports on 11 March 2026
Abstract
Cockroach allergy is a common trigger of allergic reactions and may be a cause or a result of cross-reactions with other allergens. The aim of this study was to assess the pattern of sensitisation to arthropod allergens in perennial allergic rhinitis (PAR) patients with positive skin prick test to cockroach. A group of PAR patients with positive skin prick test (SPT) result with cockroach extract (Blattella germanica) was selected. In addition to SPTs for other inhalant allergens, such as house dust mites (Dermatophagoides pteronyssinus and Dermatophagoides farinae), birch, grass, mugwort, cat, dog, and Alternaria, participants underwent the ALEX2 test which allowed for detection of sensitisation to cockroach-specific and cross-reacting molecules. Forty-eight participants took part in the study, of whom forty-six underwent the ALEX2 test. Among PAR patients with positive SPT results to cockroach extract only 2 had elevated IgE levels to cockroach specific allergens (Bla g 1 and Bla g 4). However, in substantial number of patients sensitisation to cross-reacting allergens was demonstrated. This was associated with frequent sensitisation to other arthropod extracts. A correlation was observed between cockroach allergy and allergy to edible insects such as crickets, locusts, and mealworms; seafood; house dust mites and storage mites; and wasp species, depending on the cockroach species. In our population of PAR patients’ sensitisation to cockroaches is associated with a broader spectrum of cross-reactive allergens. These findings deepen our understanding of potential cross-allergenicity and may form the basis for personalised risk assessment and allergy treatment in patients with AR.
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