Pathology, Zagazeg University.

Background: Autoimmune urticaria represents a relatively recent diagnostic advance since the discovery of histamine releasing autoantibodies against IgE and IgE receptors. Interleukin-18 (IL-18) is an immuno-regulatory cytokine and has roles in both allergic and autoimmune disorders. Aim: The aim of this work was to measure IL-18 in patients with chronic urticaria (CU) to find a correlation between IL-18 levels, clinical disease severity, autologous serum skin test (Asst) and basophil histamine releasing antibodies. Patients and methods: thirty two patients with CU and sixteen healthy control subjects were included in this study. The disease was classified according to the number and the size of wheals into mild, moderate and severe. All the patients and the controls underwent (Asst) to detect histamine releasing antibodies, basophil histamine release (BHR) assay. IL-18 levels were measured and (BHR) were assayed in the sera. Results: In this study, the mean ages of the patients ± standard mean of error (SME) was 42.6±2.6 years. The number of patients according to the severity of the disease was, mild=17, moderate=11 and severe=4 patients. The mean ± SME of IL-18 levels in pg/ml was 251.25 ± 19.69 in patients vs 215.20 ± 28.41 in healthy control with a non significant difference (P=0.29). When Asst assessment was done, 50 % of patients were scored Asst +ve and 50 % were scored Asst-ve. BHR assays were +ve in (56.25%) of Asst +ve patients and in only (12.50%) of Asst-ve patients and the mean percentage histamine release was 15.26 ± 5.6 and 6.10 ± 0.6 in both groups respectively showing a significant difference, P=0.042. IL-18 levels did not differ significantly between Asst +ve (243.75 ± 29.93 vs 258.75 ± 26.40 in Asst-ve patients, P=0.71). When IL-18 levels were compared in the groups of patients whic