Immunological Evaluation of Children with Behçet's Disease

Objective: Behçet's disease (BD) is a rare, chronic, systemic inflammatory condition characterized by features of both autoinflammation and vasculitis. This study aimed to investigate the clinical manifestations, laboratory findings, and immunological features of children with BD, and to evaluate their treatment response.Methods: A retrospective analysis was conducted of the medical records of 50 children with BD, aged 0–18 years, followed at a single pediatric rheumatology center between January 2011 and 2023. Demographic, clinical, laboratory, and immunological data were collected, including serum immunoglobulin levels (interpreted according to age-specific reference values), lymphocyte subsets, and treatment response.Results: The cohort comprised 24 males (48%) and 26 females (52%). The mean age at diagnosis was 11.12±4.24 years, with an average diagnostic delay of 2.08 years. A family history of BD was present in 20 patients (40%). Oral aphthous ulcers were the most common manifestation (96%), followed by gastrointestinal involvement and genital ulcers (each 34%), musculoskeletal involvement (58%), uveitis (18%), neurological (18%), and vascular involvement (10%). HLA-B51 was positive in 39 patients (78%), and MEFV variants in 5 of 16 tested (31.2%). Before treatment, 13 of 34 patients (38.2%) showed a reduction in at least one serum immunoglobulin (IgG in 5, IgM in 6, and IgA in 2, all below −2 SD); one patient with low IgG developed multisystem inflammatory syndrome in children (MIS-C) after COVID-19 and received intravenous immunoglobulin for 6 months. Decreased T, B, and/or natural killer (NK) cells in the lymphocyte subset were detected in 15 out of 30 patients (50%). Although changes in lymphocyte subgroup counts and/or decreased immunoglobulin levels were detected in patients with oral aphthous ulcers and gastrointestinal involvement, immune tests were normal in most patients with neurological or vascular involvement. Colchicine was the most frequently prescribed medication (90%), followed by systemic corticosteroids (24%) and biological agents (18%); clinical improvement was observed in 32 patients (64%), and of the nine patients with uveitis, eight received treatment, of whom five achieved complete recovery.Conclusion: In our study, we observed antibody deficiencies and alterations in lymphocyte subsets, particularly in patients with gastrointestinal mucosal involvement and oral and genital aphthous ulcers. These findings suggest that immunological assessment may contribute to the monitoring of children with BD; however, controlled studies are needed to determine whether it can inform treatment decisions.