CD19 and Decreased total B cell count: Monserrat et al. [17] pointed that B-cell lymphopenia affects the B-cell subsets heterogeneously, with marked reduction of CD19 + CD23 + B cells (activated regulatory B cells) and CD19 + CD5 + B cells (natural responder B-1a cells), but with normal numbers of CD19 + CD69 + early activated B cells.