Differential Th1/Th2 balance in peripheral blood lymphocytes from patients suffering from flea bite-induced papular urticaria

Background: The Th1/Th2 balance has not been characterized in patients suffering from flea bite-induced papular urticaria (FBPU). Our aim was to improve understanding of the immunopathogenesis of CD4+ and CD8+ T-cells in humans suffering from flea bite-induced papular urticaria. Methods: Peripheral blood mononuclear cells were obtained from 18 pediatric patients and 10 age-matched healthy controls. Cellular phenotypes, intracellular production of interferon gamma (IFNγ) and interleukin-4 (IL-4) in T-cells stimulated with polyclonal stimuli was determined by flow cytometry following short-term in vitro stimulation. Results: The results revealed lower frequencies of IFNγ-secreting (p = 0.02) and higher frequencies of IL-4-secreting (p = 0.03) CD4+ T-cells in patient lymphocyte cultures compared to healthy control cultures in the presence of polyclonal stimuli. This is the first description of differential cytokine patterns in papular urticaria patients. Conclusion: Patients suffering from papular urticaria have an atopic status compared to healthy children.