Phenotypic Characteristics of B-Cell Subsets in Children with Allergic Diseases

B-cell subpopulations are increasingly recognized as important modulators of immune responses, yet their role in pediatric allergic diseases remains incompletely understood. This study aimed to characterize the phenotype and frequency of peripheral B-cell subsets in children with allergic diseases and to assess their relationship with clinical and laboratory parameters. The study included 59 children with asthma, atopic dermatitis, or allergic rhinitis and 19 healthy controls. Multicolor flow cytometry was used to analyze B-cell subpopulations, including CD19⁺CD24hiCD38hi, CD19⁺CD25⁺, and IgD^-CD27⁺ cells. The children with allergic diseases exhibited significantly reduced percentages of CD19⁺CD25⁺ B cells and switched-memory B cells compared with the controls. Negative correlations were observed between selected B-cell subsets and eosinophil counts, suggesting an association with type 2 inflammation. In asthma, higher proportions of transitional B cells were associated with better disease control, whereas no significant relationship was found between B-cell subsets and atopic dermatitis severity. In allergic rhinitis, the frequency of CD19⁺CD25⁺FoxP3⁺ B cells differed according to disease control, with lower frequencies observed in children with uncontrolled compared with partially controlled disease. These findings indicate that changes in B-cell populations may be involved in the pathogenesis of allergic diseases in children and their clinical expression.