CD19 and juvenile idiopathic arthritis: However, CD19+ B cells in oligo JIA SF displayed unusual characteristics: transitional (CD38hiCD24+) and classical (CD38+CD21+) B cells were depleted in oligo JIA SF compared to control PB, while CD21lo B cells, a potentially autoreactive subclass of B cells that has been identified in other autoimmune and immune dysregulatory conditions, were enriched (Figures 3E-G) (42, 43).