CD27 and autoimmune disease: Due to the constraints of our flow cytometry panel we were unable to further discern whether a proportion of these switched cells were activated B cells (CD20+CD27+CD71+Ki-67+) committed to the memory lineage (46), CD21lo B cells (CD19+CD21loCD27+) that are committed to the PC lineage (48), or ‘double negative’ (DN) B cells (CD27-IgD-CD11c+) that have come into prominence as an expanded B cell subset in chronic infection (49) and some autoimmune diseases (17).