Omar Alberto Dominguez-Amorocho
Universidad de Santander, Colombia
Posters & Accepted Abstracts: Clin Exp Dermatol Res
Papular urticaria by flea bite (PUFB) 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. IgE and IgG can recognize antigenic proteins from complete flea extract in patients with PUFB, as in healthy individuals. The presence of eosinophils in biopsy specimens of PUFB, predominance of CD4+ T cells in lesions and IgE response suggest that an immune reaction to flea proteins in patients with PUFB is predominantly Th2. Although PUFB is defined as an allergic reaction, the immunological mechanisms underlying the process have not been clearly established. Exposure of DCs from patients to flea extract and lipopolysaccharide induced increased expression of CD83, CD86 and HLA-DR and reduced the secretion of interleukin-6 (IL-6) and IL-10 than DCs from healthy controls. Differences between systemic and local responses could be assessed by the identification of the expression of skin homing receptor called Cutaneous Lymphocyte-associated Antigen (CLA); the expression of CLA facilitates the targeting of T-cells to inflamed skin. CD4+ T cells from patients secrete IL-4, lL-10, IL-17 and IFN-�³. Patients who experienced the onset of symptoms within the first 5 years of age show a greater frequency of local CD4+CLA+ IL-4- and IL- 17-producing T-cells, patients who experienced the onset of symptoms after the age of 5 years have a higher frequency of CD4+CLA- IL-10 producing cells suggesting a systemic control mechanism contributing to the acquisition of tolerance to flea antigens.
Email: oadominguez80@gmail.com
