Papular Urticaria: Insights into Non—IgE-mediated Hypersensitivity Reactions Produced by Stings of Culex spp and Aedes spp in Patients with Intrinsic Atopic Dermatitis

Aims: To evaluate the contribution of non—IgE-mediated hypersensitivity mechanisms in Papular Urticaria produced by Aedes spp and Culex spp bites in patients diagnosed with Intrinsic Atopic Dermatitis coming from an urban (not beachy) Brazilian region.

Study Design: To better understand the relationship between Papular Urticaria and Atopic Dermatitis, we revisit, through a retrospective chart review, the precipitins titrations and the ex vivo challenge tests against Aedes spp and Culex spp body extracts performed in patients with non—IgE-mediated Papular Urticaria who also were diagnosed with Intrinsic Atopic Dermatitis.

Place and Duration of Study: Instituto Alergoimuno de Americana – São Paulo – Brazil – between January 2018 and March 2023.

Methodology: We examined the medical charts of a population of 48 patients diagnosed with Intrinsic Atopic Dermatitis and non—IgE-mediated Papular Urticaria who were investigated through the research of precipitins and/or the Leukocyte Adherence Inhibition Test (LAIT) against Aedes spp and Culex spp body extracts. Cascade distribution charts were mounted with the range groups of Leukocyte Adherence Inhibition (LAI) results of ex vivo Culex spp and Aedes spp body extract challenges monitored by LAIT.

Results: The Cascade distribution charts showed a very wide distribution of results of LAIT performed with the Culex spp. However, most results (66.7%) were distributed above a 40% LAI, which suggests it may possess a good potential for the LAIT as a diagnostic indicator. However, the Cascade distribution charts for the LAIT performed with Aedes spp showed 100% of the cases with an LAI above 40%, which suggests it may possess an excellent potential as a diagnostic indicator. There was only one case where the precipitins research was negative for both allergens.

Conclusion: Our results support the fact that there is a strong relationship between non—IgE-mediated Papular Urticaria and Intrinsic Atopic Dermatitis, which probably share a common immune physiopathology.