Breg cells were mostly studied in ANCA-associated vasculitis, and found to be decreased.37–39Percentages of IL-10+Breg cells and CD5+CD24highCD38high Breg cells were decreased in active ANCA-associated vasculitis and returned to normal in disease remission with concomitant decrease in serum ANCA levels.39In another study, CD5+CD19+ B cells were decreased in active disease, returned to normal during disease remission, and decreased before disease relapse.37These findings suggest that IL-10+Breg cells could be used as biomarkers in ANCA-associated vasculitis. Here, CD5 is linked to anti-neutrophil cytoplasmic antibody-associated vasculitis.