LAUSR

Dear Editor, The pathogenesis of chronic urticaria (CU) is characterized by a multiplicity of mechanisms, including autoimmunity, autoallergy, and coagulation each of interlinked rather than independent events. Osteopontin (OPN) is a multifunctional protein produced by many immune system cells. Although the distribution of OPN within normal tissue is limited, its expression increases in inflammatory and allergic conditions. It was shown in murine fetal skin that OPN is produced by mast cells, indicating that OPN is a mast cell mediator, and it enhances mast cell responses to antigens. Therefore, OPN might influence mast cell-related pathological conditions such as CU. There is emerging evidence to support an active role for OPN in Th2-linked inflammation and allergic disease. OPN is expressed and functional in peripheral blood eosinophils of atopic human subjects. Samitas et al found OPN levels in bronchoalveolar lavage fluid and serum samples to be higher in asthma patients compared to controls. Elevated levels of OPN were also detected in other allergic conditions. Our case-control study included 34 patients and 34 age and sexmatched healthy controls (Table 1). Patients having a coexisting systemic disease, infection, malignancy, and receiving immunosuppressive, systemic steroid and/or systemic antihistaminic or ketotifen therapies within the last 2 months, the last 4 weeks and last week, respectively, were excluded. The diagnosis of physical urticaria was based on clinical examination and anamnesis. Urticarial activity was estimated according to the number of wheals scored as follows: 0 = no wheals; 1 = 1 to 10 small (<3 cm in diameter) wheals; 2 = 10 to 50 small wheals or 1 to 10 large wheals; 3 = more than 50 small wheals or 10 to 50 large wheals; and 4 = totally covered with wheals. Pruritus severity was scored as no pruritus (0), mild (1), moderate (2), and severe (3). Plasma OPN levels were studied by enzyme immunometric assay method. Nonlesional and urticarial plaque skin samples were obtained from 20 patients who consented to a biopsy. Five healthy donors who had undergone abdominoplasty were used as controls. OPN expression was investigated by immunohistochemical analysis. One patient's skin samples were excluded because of technical reasons. The mean ± SD plasma OPN levels of patients were higher than controls (61.03 ± 17.99 vs 45.94 ± 15.81 ng/mL, P < .001) (Figure 1) and showed a negative correlation with patient age and a positive correlation with disease duration, disease severity and pruritus severity (Table 2). While intercellular epidermal and/or dermal OPN expression was identified in 18 nonlesional (94.7%) and in 18 urticarial (94.7%) lesions of patients, none of five control skin samples showed OPN expression (P < .001). Intracellular OPN expression was identified for