Increased CD5+CD19+ B lymphocytes at the onset of type 1 diabetes in children.

The aim of this study was to determine whether the proportion of circulating B cells expressing the differentiative antigen CD5 was increased in children affected by type 1 diabetes, and whether the number of these cells was correlated with the presence of anti-islet cell autoantibodies. Sixteen children affected by insulin-dependent diabetes mellitus (type 1) were investigated for the presence of B lymphocytes bearing the CD5 surface molecule, T-cell-specific activation markers, organ- and nonorgan-specific autoantibodies. The number of CD5+CD19+ cells was higher in type 1 children with a very recent onset of the disease, as compared with patients on insulin therapy for more than 30 days and controls (P < 0.05). No correlation was found between the number of CD5+CD19+ cells and the presence of either organ- or nonorgan-specific autoantibodies. Our results indicate that CD5+CD19+ cells are involved in the pathogenesis of type 1 diabetes in children. A potential immunoregulatory role of this B cell population is discussed.