• Omar Dominguez-Amorocho, Silvia Duarte, John Mario González, Evelyne Halpert, María Claudia Ortega, Adriana Rodríguez, Elizabeth García, and Adriana Cuellar.
• Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá, Colombia.
• Int. Arch. Allergy Immunol. 2013 Jan 1; 160 (2): 165-72.

BackgroundPapular 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.MethodsCell 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.ResultsTotal 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.ConclusionAnalysis 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.Copyright © 2012 S. Karger AG, Basel.

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