We, therefore, performed a detailed analysis of B cell subsets to determine the frequency of tetramer-binding B cells in antigen-inexperienced (CD27−IgD+), or antigen-experienced subsets including IgD+CD27+ and Ig-class-switched (IgD−CD27+) memory cell subsets and plasmablasts (CD27++CD19low) in individual patients with SLE. This evidence concerns the gene CD27 and systemic lupus erythematosus.