Influence of narrowband UVB irradiation of serum on autologous serum skin test results.

Background  Autologous serum skin test (ASST) is an in vivo test to demonstrate circulating endogenous proinflammatory or wheal-inducing factors in urticaria patients. While ASST was negative in a patient with solar urticaria and in a patient with localized heat urticaria, test results turned to positive when performed with visible light-irradiated and heated serums, respectively. These data suggest that some factors and/or antibodies in serum may be activated or inhibited with different factors. We aimed to investigate whether or not ASST results change when performed with narrowband ultraviolet B (UVB)-irradiated serum. Materials and methods  Seventy-seven patients with chronic idiopathic urticaria underwent ASST twice in consecutive days. The second ASST was performed with narrowband UVB-irradiated serum. The results of the first and second ASSTs were compared. Results  The first ASST results were positive in 46 (59.7%) patients. ASST results reversed oppositely in 36 (46.8%) patients, turned from negative to positive in 19 patients, and turned from positive to negative in 17 patients when performed with narrowband UVB-irradiated serum. Conclusion  Our results suggest that narrowband UVB may have modifying effects on some wheal-inducing factors and/or antibodies. On which factors in serum narrowband UVB has effects may be investigated.