TNFRSF13B and infection: Following infection, B-1 cells in the spleens of A/J mice maintained high levels of BAFFR and TACI expression and expressed higher levels of surface CD138 relative to C57BL/6J mice (Fig 6D and 6E), markers known to be induced by Nfkbid and important for B cell activation and differentiation into antibody secreting cells [37].