Background: Persistent antigenic stimulation due to repeated exposure to nickel may lead to chronic inflammation resulting in allergic contact dermatitis (ACD).Objectives: This study was performed to assess nickel induced immune activation among patients sensitized against nickel.Patients and Methods: A total of 35 patients (29 females and 6 males; mean age 36±9 years) with nickel contact dermatitis and 20 patch test negative healthy individuals (14 females and 6 males; mean age 29±7 years) were included in this study. Peripheral blood of patients and controls was incubated with nickel sulfate for 24 hours. Immune activation was assessed by CD69 up-reg- ulation on T lymphocyte sub-sets by flow cytometry.Results: Base line expression of CD69 on CD8+ lymphocytes was higher among patients compared to controls (4.1±1.3%vs2.8±1.1%;p<0.009). There was no difference in proportions of CD±CD69+ cells between patients and controls (3.2±0.9%vs2.3±0.8%). Exposure to nickel induced expression of CD69 on a significantly higher proportion of CD4+ lympho- cytes (22.1±6.2%) of the ACD patients compared to controls (2.8±2.5%;p<0.0001). Similarly nickel induced CD69 expression on a higher proportion of CD8+ lymphocytes (18.2±5.3%) from ACD patients compared to the controls (1.9±1.8%;p<0.0006).Conclusion: CD69 molecule appears to be an important regulator of immune response in nickel contact dermatitis. Keywords: Nickel, CD4+, CD8+, CD69, contact dermatitis
