Differences in Systemic and Skin Migrating-Specific CD4⁺ T Cells in Papular Urticaria by Flea Bite

Abstract

Background: Papular urticaria by flea bite is a chronic allergic condition in which clinical improvement may occur at the age of 7 years, thus representing a natural model of acquired immunologic tolerance in humans. The aim of this study was to characterize regulatory cells and specific responses to flea antigens of CD4⁺ T lymphocytes expressing cutaneous migration markers in patients with papular urticaria caused by flea bite and with different disease evolution times. Methods: Cell populations were characterized by flow cytometry in samples from patients and healthy controls. Specific cell stimulation was performed with a complete flea body extract. The Mann-Whitney U test was used for comparisons. Results: Total dendritic cells were lower in patients than in healthy controls. No quantitative differences were found in CD4 regulatory T cells. CD4⁺ T cells from patients produced more IL-4, lL-10, IL-17, and IFN-γ. Patients who experienced the onset of symptoms within the first 5 years of age showed a greater percentage of local (cutaneous lymphocyte antigen +) IL-4- and IL-17-producing cells, while patients who experienced the onset of symptoms after the age of 5 years had a higher percentage of systemic (cutaneous lymphocyte antigen –) IL-10-producing cells. Conclusion: Analysis of the cellular immune response against whole flea antigen in patients with papular urticaria by flea bites suggests a possible participation of inflammatory cytokines in the skin reaction (Th17) and a systemic control mechanism (IL-10). This pattern of cytokine production in patients could be a consequence of an impaired dendritic cell population.

Prevalence of papular urticaria caused by flea bites and associated factors in children 1–6 years of age in Bogotá, D.C.

“…In the present study, a prevalence of papular urticaria of 20.3% was observed in children between 1 and 6 years of age. This prevalence is high in comparison to the prevalence reported in previous studies, and it could be due to several of those reports included children with a higher average age [ 13 – 15 ], and it has been reported a reduction in the immunological reaction to insect bite after the seventh year of life [ 2 , 19 ].…”

“…Others risk factors were the use of public transport for transportation of the children, the use of mattresses without springs or foam lining, and the detection of fleas inside the accommodation (Table 2 ). Among the risk factors, we would highlight the presence of fleas in view of the fact that patients attending the Pediatric Dermatology and Allergy division of the Fundación Santa Fe de Bogotá D.C. have showed papular urticaria immune and histopathological reactions when exposed to flea antigens [ 3 , 16 , 19 ]. These results support that fleas can be involved in those reactions of papular urticaria frequently diagnosed in this dermatological practice all year round.…”

Updates in Papular Urticaria Causes, Diagnosis, And Management: A Systematic Review

“…A total of 8 studies were included in this review, with 527 patients with papular urticaria. Four studies were conducted in Colombia [12][13][14]16 , one in the USA 10 , one in Egypt 11 , one in Pakistan 15 , and one in South Africa 17 . Regarding the studies' designs, Four studies were case-controls 13,16 , two were crosssectional 11,12 , one was a clinical trial 10 , and one was a prospective study 17 .…”

Years in Review: Recent Progress in Cellular Allergology

“…Interestingly, after more than 5 years of disease duration, skin-homing CLA4 + T cells lost their capacity to produce IL-4, while they largely maintained their IL-10 and IL-17 secretion capacity. Compatible with this hypothesis, the frequency of IFN-γ-positive T cells was reduced in both skin-homing and non-skin-homing lymphocytes in such patients [16]. …”