The CD19+CD20+ B cell pool in this cluster consisted of greater relative proportions of CD19+CD27−CD24brightCD38bright transitional B cells (6.3% ± 9.0%) and CD19+CD20+CD27− naïve B cells (85.4% ± 7.2%) and lower proportions of CD19+CD20−CD138+ long-lived plasma cells (0.2% ± 0.3%) and CD19+CD38brightCD27bright SLE-associated plasma cells (1.6% ± 2.0%) compared with cluster 1 [(2.1% ± 3.1%), (56.8% ± 11.5%), (0.7% ± 1.0%), and (6.6% ± 7.0%), respectively] and cluster 3 [(5.0% ± 7.5%), (81.8% ± 9.2%), (0.4% ± 0.5%), and (3.6% ± 4.0%), respectively]. This evidence concerns the gene CD27 and systemic lupus erythematosus.