CD19 and systemic lupus erythematosus: IGHV4-34 was, however, enriched in CD19+CD27+IgD+ and CD19+IgD−CD27−CD38mid/hi populations to a level similar to that seen in SLE patients (Fig. 7b), and consistent with impaired post-immune tolerance associated with FcγRIIB dysfunction, though this difference was not seen in the CD19+IgD−CD27+CD38low/mid population.