Increased proportion of CD3+CD4-CD8- double-negative T cells in peripheral blood of children with Behcet's disease

INTRODUCTION: Behcet's disease (BD) is a multi-system inflammatory disorder of poorly understood pathogenesis, which is characterized by oral aphtosis, genital ulcers and uveitis. OBJECTIVE: To assess the role of CD3+CD4-CD8- double negative (DN) T cells in pathogenesis of Behcet's disease. PATIENTS: Ten BD patients (age 12.2+/-2.2 years, 7 in remission, 3 in exacerbation state) treated at the Pediatric Rheumatology unit of Soroka University Medical Center and 3 age-matched controls participated in the study. METHODS: Peripheral blood lymphocytes of study subjects were isolated and stained with fluorescein-labeled anti-CD45, CD3, CD4, CD8 antibodies and analyzed by FACS assay. RESULTS: Proportion of CD4-CD8- DN T cells was significantly increased in BD patients (n=10) as compared to healthy controls (6.2+/-3.4% vs. 3.2+/-1.1% of total CD3+ cells, p<0.05), this cell group was additionally enhanced in BD exacerbation, compared to patients in remission (10+/-4.1% vs. 4.7+/-1.2%, p<0.05, respectively). DN T cells were significantly increased in BD patients in remission, compared to healthy controls (4.7+1.2% vs. 3.2+1.1% of total CD3+ cells, p<0.05, respectively). CONCLUSIONS: Behcet's disease is characterized by increased proportion of CD3+CD4-CD8- double negative T cells in peripheral blood. Further studies, that include additional immunophenotyping and analysis of gene expression, aimed at characterization of these cells are currently underway.